Pub Date : 2026-01-06DOI: 10.1016/j.jinorgbio.2026.113215
Dona Imanga Upamadi Edirisinghe , Prerana Dash , Jiawen Yang , Sreerag N. Moorkkannur , Deepa Neupane , Jithma Gethmini Piyasara Sriwardana Dissanayake , Alexis Eckhart , Katlyn Meier , Rajeev Prabhakar , Olga V. Makhlynets
Metallohydrolases use metal cations in their active sites to catalyze the hydrolytic cleavage of biological substrates. We used a simple model protein Due Ferri single chain (DFsc) in combination with Mn-Mn and Zn-Zn to study the effect of the nature of metal ions on its reactivity. The ICP-OES analysis confirmed the metal ion binding with desired ratios. The Mn2-DFsc showed the highest hydrolytic activity with a catalytic efficiency (kcat/Km) of 6.5 M−1 min−1. EPR analysis of the di‑manganese DFsc indicates that two manganese centers are antiferromagnetically coupled in a S = 0 ground state. Based on both experimental and computational results, a mechanism of phosphoester hydrolysis is proposed, in which the substrate binds to Mn terminally, and follows an associative/dissociative mechanism with hydrolysis assisted by nucleophilic attack of the bridging OH nucleophile. The findings from this study can be used to further optimize the DFsc scaffold for designing artificial enzymes for bioremediation of multiple hazardous molecules.
{"title":"Phosphoester hydrolysis using a de novo designed protein: A combined experimental and computational study","authors":"Dona Imanga Upamadi Edirisinghe , Prerana Dash , Jiawen Yang , Sreerag N. Moorkkannur , Deepa Neupane , Jithma Gethmini Piyasara Sriwardana Dissanayake , Alexis Eckhart , Katlyn Meier , Rajeev Prabhakar , Olga V. Makhlynets","doi":"10.1016/j.jinorgbio.2026.113215","DOIUrl":"10.1016/j.jinorgbio.2026.113215","url":null,"abstract":"<div><div>Metallohydrolases use metal cations in their active sites to catalyze the hydrolytic cleavage of biological substrates. We used a simple model protein Due Ferri single chain (DFsc) in combination with Mn-Mn and Zn-Zn to study the effect of the nature of metal ions on its reactivity. The ICP-OES analysis confirmed the metal ion binding with desired ratios. The Mn<sub>2</sub>-DFsc showed the highest hydrolytic activity with a catalytic efficiency (k<sub>cat</sub>/K<sub>m</sub>) of 6.5 M<sup>−1</sup> min<sup>−1</sup>. EPR analysis of the di‑manganese DFsc indicates that two manganese centers are antiferromagnetically coupled in a S = 0 ground state. Based on both experimental and computational results, a mechanism of phosphoester hydrolysis is proposed, in which the substrate binds to Mn terminally, and follows an associative/dissociative mechanism with hydrolysis assisted by nucleophilic attack of the bridging OH nucleophile. The findings from this study can be used to further optimize the DFsc scaffold for designing artificial enzymes for bioremediation of multiple hazardous molecules.</div></div>","PeriodicalId":364,"journal":{"name":"Journal of Inorganic Biochemistry","volume":"277 ","pages":"Article 113215"},"PeriodicalIF":3.2,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146008219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-06DOI: 10.1016/j.jinorgbio.2026.113224
Trevor D. Rapson , Xueqin Wang , Jessica K. Bilyj , Christina M. Gregg , Ingrid Venables , Anu Mathew , Julien Langley , Nicholas Cox , Guy N.L. Jameson , Craig C. Wood
The extreme oxygen sensitivity of nitrogenase enzymes poses a major obstacle to their use in biotechnology, particularly in engineering nitrogen-fixing plants. While the vulnerability of nitrogenase components NifH and NifDK to oxygen is well established, the sensitivity of the metal clusters on scaffold proteins involved in nitrogenase biosynthesis has not been previously reported. In this study, we investigate the oxygen sensitivity of the [4Fe-4S] clusters on the scaffold protein NifU, which supplies these clusters to several downstream targets, including NifH. Using UV/Vis, Mössbauer, and Electron Paramagnetic Resonance (EPR) spectroscopy, we show that exposure to oxygen converts the [4Fe-4S] clusters into [2Fe-2S] clusters. This degradation occurs rapidly, even at low oxygen levels (2 %). However, a fraction of the [4Fe-4S] clusters remain intact under these conditions, allowing NifU to activate apo-NifH by transferring functional clusters. In contrast, at atmospheric oxygen levels (21 %), all [4Fe-4S] clusters are damaged over 10 min, and NifU quickly loses its ability to reactivate apo-NifH.
{"title":"The oxygen sensitivity of [4Fe-4S] clusters on the nitrogenase scaffold protein NifU","authors":"Trevor D. Rapson , Xueqin Wang , Jessica K. Bilyj , Christina M. Gregg , Ingrid Venables , Anu Mathew , Julien Langley , Nicholas Cox , Guy N.L. Jameson , Craig C. Wood","doi":"10.1016/j.jinorgbio.2026.113224","DOIUrl":"10.1016/j.jinorgbio.2026.113224","url":null,"abstract":"<div><div>The extreme oxygen sensitivity of nitrogenase enzymes poses a major obstacle to their use in biotechnology, particularly in engineering nitrogen-fixing plants. While the vulnerability of nitrogenase components NifH and NifDK to oxygen is well established, the sensitivity of the metal clusters on scaffold proteins involved in nitrogenase biosynthesis has not been previously reported. In this study, we investigate the oxygen sensitivity of the [4Fe-4S] clusters on the scaffold protein NifU, which supplies these clusters to several downstream targets, including NifH. Using UV/Vis, Mössbauer, and Electron Paramagnetic Resonance (EPR) spectroscopy, we show that exposure to oxygen converts the [4Fe-4S] clusters into [2Fe-2S] clusters. This degradation occurs rapidly, even at low oxygen levels (2 %). However, a fraction of the [4Fe-4S] clusters remain intact under these conditions, allowing NifU to activate apo-NifH by transferring functional clusters. In contrast, at atmospheric oxygen levels (21 %), all [4Fe-4S] clusters are damaged over 10 min, and NifU quickly loses its ability to reactivate apo-NifH.</div></div>","PeriodicalId":364,"journal":{"name":"Journal of Inorganic Biochemistry","volume":"277 ","pages":"Article 113224"},"PeriodicalIF":3.2,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145964745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-05DOI: 10.1016/j.jinorgbio.2026.113216
Hou Zhu , Yong-Sheng Yang , Lin-Yuan Zhu, Chun-Rong Jiang, Zheng Zhang, Meng-Ting Xu, Rong-Tao Li, Rui-Rong Ye
Four novel Ir(III)/Re(I)-1-methyl-D-tryptophan conjugates (Ir-MT-1–2 and Re-MT-1–2) were designed and synthesized for the first time, among which 1-methyl-D-tryptophan (1-MT) is an indoleamine 2,3-dioxygenase (IDO) inhibitor. Three (Ir-MT-1–2 and Re-MT-1) of the metal-conjugates showed high-efficient anti-tumor activities against human cervical cancer HeLa cells, with IC50 values of 5.2, 7.1, and 4.4 μM, respectively, and significantly inhibited IDO expression. Mechanistic investigations revealed that these complexes selectively localized to mitochondria, inducing mitochondrial membrane potential (MMP) depolarization, elevating intracellular reactive oxygen species (ROS) levels, activating mitochondrial apoptotic pathways, and simultaneously inducing the cleavage of pyroptosis marker (GSDME) to cause pyroptosis. These results demonstrate the potential of combing transition metals with IDO inhibitors for cancer treatment.
{"title":"Iridium(III) and rhenium(I) complexes containing an IDO inhibitor induce apoptosis and pyroptosis","authors":"Hou Zhu , Yong-Sheng Yang , Lin-Yuan Zhu, Chun-Rong Jiang, Zheng Zhang, Meng-Ting Xu, Rong-Tao Li, Rui-Rong Ye","doi":"10.1016/j.jinorgbio.2026.113216","DOIUrl":"10.1016/j.jinorgbio.2026.113216","url":null,"abstract":"<div><div>Four novel Ir(III)/Re(I)-1-methyl-D-tryptophan conjugates (<strong>Ir-MT-1</strong>–<strong>2</strong> and <strong>Re-MT-1</strong>–<strong>2</strong>) were designed and synthesized for the first time, among which 1-methyl-D-tryptophan (1-MT) is an indoleamine 2,3-dioxygenase (IDO) inhibitor. Three (<strong>Ir-MT-1</strong>–<strong>2</strong> and <strong>Re-MT-1</strong>) of the metal-conjugates showed high-efficient anti-tumor activities against human cervical cancer HeLa cells, with IC<sub>50</sub> values of 5.2, 7.1, and 4.4 μM, respectively, and significantly inhibited IDO expression. Mechanistic investigations revealed that these complexes selectively localized to mitochondria, inducing mitochondrial membrane potential (MMP) depolarization, elevating intracellular reactive oxygen species (ROS) levels, activating mitochondrial apoptotic pathways, and simultaneously inducing the cleavage of pyroptosis marker (GSDME) to cause pyroptosis. These results demonstrate the potential of combing transition metals with IDO inhibitors for cancer treatment.</div></div>","PeriodicalId":364,"journal":{"name":"Journal of Inorganic Biochemistry","volume":"277 ","pages":"Article 113216"},"PeriodicalIF":3.2,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145921998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-03DOI: 10.1016/j.jinorgbio.2026.113212
Yehong Tan , Tao Yang , Siran Jiang , Shumeng Li , Linxiang Cai , Ying Wang , Zijian Guo , Xiaoyong Wang
Immunosuppressive tumor microenvironment is the major obstacle for antitumor immunotherapy. Elimination of myeloid-derived suppressor cells (MDSCs) potentiates immunotherapy for various solid tumors. Oxaliplatin-artesunate complex OPA decreases MDSCs by inhibiting CD33 and the triggering receptor expressed on myeloid cells 2 (TREM2) in the TME, and enhancing dendritic cell maturation due to its ability to facilitate immunogenic cell death and activate the cyclic-GMP-AMP synthase–stimulator of interferon genes (cGAS-STING) pathway. Moreover, OPA upregulates the costimulatory molecule CD28 and downregulates the immune checkpoint cytotoxic T lymphocyte-associated protein 4 (CTLA-4) on T cells, thus impeding the T cell depletion and immunosuppression. The activation of immune circulation and immunosignal pathway increases the chemotherapeutic activity of parent oxaliplatin. In addition, OPA serves as a cancer vaccine to inhibit tumor metastasis and reoccurrence. Lastly, the stability and safety profiles are superior to that of oxaliplatin. OPA is a unique chemoimmunotherapeutic agent with a distinct mechanism of action and prominent efficacy on orthotopic colorectal cancer in mouse models.
{"title":"Oxaliplatin-artesunate conjugate intensifies suppression on colorectal cancer by boosting antitumor immunity","authors":"Yehong Tan , Tao Yang , Siran Jiang , Shumeng Li , Linxiang Cai , Ying Wang , Zijian Guo , Xiaoyong Wang","doi":"10.1016/j.jinorgbio.2026.113212","DOIUrl":"10.1016/j.jinorgbio.2026.113212","url":null,"abstract":"<div><div>Immunosuppressive tumor microenvironment is the major obstacle for antitumor immunotherapy. Elimination of myeloid-derived suppressor cells (MDSCs) potentiates immunotherapy for various solid tumors. Oxaliplatin-artesunate complex OPA decreases MDSCs by inhibiting CD33 and the triggering receptor expressed on myeloid cells 2 (TREM2) in the TME, and enhancing dendritic cell maturation due to its ability to facilitate immunogenic cell death and activate the cyclic-GMP-AMP synthase–stimulator of interferon genes (cGAS-STING) pathway. Moreover, OPA upregulates the costimulatory molecule CD28 and downregulates the immune checkpoint cytotoxic T lymphocyte-associated protein 4 (CTLA-4) on T cells, thus impeding the T cell depletion and immunosuppression. The activation of immune circulation and immunosignal pathway increases the chemotherapeutic activity of parent oxaliplatin. In addition, OPA serves as a cancer vaccine to inhibit tumor metastasis and reoccurrence. Lastly, the stability and safety profiles are superior to that of oxaliplatin. OPA is a unique chemoimmunotherapeutic agent with a distinct mechanism of action and prominent efficacy on orthotopic colorectal cancer in mouse models.</div></div>","PeriodicalId":364,"journal":{"name":"Journal of Inorganic Biochemistry","volume":"277 ","pages":"Article 113212"},"PeriodicalIF":3.2,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145921913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The COVID-19 pandemic, driven by SARS-CoV-2, has underscored the urgent need for effective antiviral agents. Research targeting the main protease (3CLpro), a crucial enzyme in the viral replication process, offers a promising strategy for antiviral drug development. Metals are not only fundamental to the human body but also central to the field of inorganic biochemistry. In this study, we report the design and synthesis of a novel polypyridyl di‑copper coordination complex with superior structural stability and antiviral activity, and characterized by various analytical and spectral techniques. Among the tested compounds, the tetrapyridine‑copper complex (B2) featuring a nitrate counterion demonstrated exceptional inhibition of 3CLpro and tolerable cytotoxicity. The strong CuCu synergy enables it to adopt a more compact conformation and establish favorable interactions with 3CLpro. These attributes position it as a compelling candidate for future antiviral therapeutics. Additionally, molecular docking, molecular dynamics simulations, and free energy calculations were employed to elucidate the binding interactions and identify key residues for inhibitor optimization.
{"title":"Copper-polypyridine complexes as potent SARS-CoV-2 3CLpro inhibitors: Synthesis, evaluation, and molecular basis based on computational study","authors":"Xiaolin Jiang , Haoyu Zhang , Shiyu Ping , Yaru Zou , Liguang Zhang","doi":"10.1016/j.jinorgbio.2026.113214","DOIUrl":"10.1016/j.jinorgbio.2026.113214","url":null,"abstract":"<div><div>The COVID-19 pandemic, driven by SARS-CoV-2, has underscored the urgent need for effective antiviral agents. Research targeting the main protease (3CL<sup>pro</sup>), a crucial enzyme in the viral replication process, offers a promising strategy for antiviral drug development. Metals are not only fundamental to the human body but also central to the field of inorganic biochemistry. In this study, we report the design and synthesis of a novel polypyridyl di‑copper coordination complex with superior structural stability and antiviral activity, and characterized by various analytical and spectral techniques. Among the tested compounds, the tetrapyridine‑copper complex (<strong>B2</strong>) featuring a nitrate counterion demonstrated exceptional inhibition of 3CL<sup>pro</sup> and tolerable cytotoxicity. The strong Cu<img>Cu synergy enables it to adopt a more compact conformation and establish favorable interactions with 3CL<sup>pro</sup>. These attributes position it as a compelling candidate for future antiviral therapeutics. Additionally, molecular docking, molecular dynamics simulations, and free energy calculations were employed to elucidate the binding interactions and identify key residues for inhibitor optimization.</div></div>","PeriodicalId":364,"journal":{"name":"Journal of Inorganic Biochemistry","volume":"277 ","pages":"Article 113214"},"PeriodicalIF":3.2,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145921995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-03DOI: 10.1016/j.jinorgbio.2026.113213
Matthew S. Hursey , Abigail D. Reitz , Samuel E. Fidler, Sarah L.J. Michel
Zinc finger Ran-binding domain-containing protein 2 (ZRANB2) is an RNA-binding protein that plays a key role in alternative splicing. It contains two N-terminal RanBP2-type ZF domains in which four cysteine residues coordinate Zn(II) in a tetrahedral geometry to afford proper folding and function. Persulfidation, a post-translational modification in which cysteine thiols (-SH) are converted to persulfides (-SSH) by hydrogen sulfide (H2S), has emerged as a means for regulating ZF activity. ZRANB2 is frequently identified as persulfidated in chemoselective proteomics screens, and here, we evaluate the direct modification of ZRANB2 by H2S. Using a recombinantly expressed two-domain construct (ZRANB2-2D), we report that Zn(II)-bound ZRANB2-2D undergoes persulfidation when exposed to H2S and oxygen with superoxide generated as an intermediate. This modification induces a loss of Zn(II)-dependent structure and abrogates binding to an RNA oligonucleotide from exon 3 of the transformer-2 protein homolog beta (TRA2B) RNA, a splicing target of ZRANB2, as well as to an optimized RNA oligonucleotide. Consistent with impaired RNA binding, cellular treatment with H2S leads to decreased formation of a TRA2B splice product, suggesting a connection to persulfidation of ZRANB2 in cells. Notably, addition of a reductant restores ZRANB2-2D RNA-binding activity in vitro. These results position persulfidation as a rheostat for modulating ZF protein function, exemplified here by its role in regulating ZRANB2 RNA binding and splicing.
{"title":"Persulfidation of the zinc finger protein ZRANB2 modulates its RNA binding and alternative splicing function","authors":"Matthew S. Hursey , Abigail D. Reitz , Samuel E. Fidler, Sarah L.J. Michel","doi":"10.1016/j.jinorgbio.2026.113213","DOIUrl":"10.1016/j.jinorgbio.2026.113213","url":null,"abstract":"<div><div>Zinc finger Ran-binding domain-containing protein 2 (ZRANB2) is an RNA-binding protein that plays a key role in alternative splicing. It contains two N-terminal RanBP2-type ZF domains in which four cysteine residues coordinate Zn(II) in a tetrahedral geometry to afford proper folding and function. Persulfidation, a post-translational modification in which cysteine thiols (-SH) are converted to persulfides (-SSH) by hydrogen sulfide (H<sub>2</sub>S), has emerged as a means for regulating ZF activity. ZRANB2 is frequently identified as persulfidated in chemoselective proteomics screens, and here, we evaluate the direct modification of ZRANB2 by H<sub>2</sub>S. Using a recombinantly expressed two-domain construct (ZRANB2-2D), we report that Zn(II)-bound ZRANB2-2D undergoes persulfidation when exposed to H<sub>2</sub>S and oxygen with superoxide generated as an intermediate. This modification induces a loss of Zn(II)-dependent structure and abrogates binding to an RNA oligonucleotide from exon 3 of the transformer-2 protein homolog beta (TRA2B) RNA, a splicing target of ZRANB2, as well as to an optimized RNA oligonucleotide. Consistent with impaired RNA binding, cellular treatment with H<sub>2</sub>S leads to decreased formation of a TRA2B splice product, suggesting a connection to persulfidation of ZRANB2 in cells. Notably, addition of a reductant restores ZRANB2-2D RNA-binding activity in vitro. These results position persulfidation as a rheostat for modulating ZF protein function, exemplified here by its role in regulating ZRANB2 RNA binding and splicing.</div></div>","PeriodicalId":364,"journal":{"name":"Journal of Inorganic Biochemistry","volume":"277 ","pages":"Article 113213"},"PeriodicalIF":3.2,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146008309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-02DOI: 10.1016/j.jinorgbio.2025.113209
Jiaqing Xu , Lu Yu , Sheng-Song Yu , Yiwei Liu , Jing-Xiang Wang , Jun-Jie Li , Casey Van Stappen , Han-Qing Yu , Mark J. Nilges , Yi Lu
Cupredoxins are a family of copper proteins that mediate electron transfer in key biological processes, and understanding structural features responsible for their spectroscopic properties is important for elucidating structure–function relationships. Here, we characterize the effect of mutation of the axial methionine to histidine in azurin from Pseudomonas aeruginosa (M121HAz-PA) using UV–Vis absorption, electron paramagnetic resonance (EPR) spectroscopy, and X-ray crystallography to examine how the same M121H mutation affects spectroscopic properties differently from its homolog in Alcaligenes denitrificans (M121HAz-AD). M121HAz-PA shows a pH-dependent UV–vis spectral change from pH 4 to pH 8, with unusual EPR features, indicating changes in coordination electronic structure. Azide binding titrations produce EPR spectra intermediate between type 1 copper (T1Cu) and type 2 copper (T2Cu), supporting that changes of (exogenous) ligand coordination drive significant geometric and electronic rearrangements. X-ray crystallography reveals differences in axial His121 coordination mode to CuII and its orientation between M121HAz-PA and M121HAz-AD, providing a structural basis for the observed spectroscopic differences. These findings provide insights into how subtle variations in ligand coordination affect the electronic structure in Cu-binding sites, offering a basis for the rational design of metalloproteins.
{"title":"Structural basis for organism-dependent effects on spectroscopic properties of type 1 copper azurin by the same axial methionine to histidine mutation","authors":"Jiaqing Xu , Lu Yu , Sheng-Song Yu , Yiwei Liu , Jing-Xiang Wang , Jun-Jie Li , Casey Van Stappen , Han-Qing Yu , Mark J. Nilges , Yi Lu","doi":"10.1016/j.jinorgbio.2025.113209","DOIUrl":"10.1016/j.jinorgbio.2025.113209","url":null,"abstract":"<div><div>Cupredoxins are a family of copper proteins that mediate electron transfer in key biological processes, and understanding structural features responsible for their spectroscopic properties is important for elucidating structure–function relationships. Here, we characterize the effect of mutation of the axial methionine to histidine in azurin from <em>Pseudomonas aeruginosa</em> (M121HAz-PA) using UV–Vis absorption, electron paramagnetic resonance (EPR) spectroscopy, and X-ray crystallography to examine how the same M121H mutation affects spectroscopic properties differently from its homolog in <em>Alcaligenes denitrificans</em> (M121HAz-AD). M121HAz-PA shows a pH-dependent UV–vis spectral change from pH 4 to pH 8, with unusual EPR features, indicating changes in coordination electronic structure. Azide binding titrations produce EPR spectra intermediate between type 1 copper (T1Cu) and type 2 copper (T2Cu), supporting that changes of (exogenous) ligand coordination drive significant geometric and electronic rearrangements. X-ray crystallography reveals differences in axial His121 coordination mode to Cu<sup>II</sup> and its orientation between M121HAz-PA and M121HAz-AD, providing a structural basis for the observed spectroscopic differences. These findings provide insights into how subtle variations in ligand coordination affect the electronic structure in Cu-binding sites, offering a basis for the rational design of metalloproteins.</div></div>","PeriodicalId":364,"journal":{"name":"Journal of Inorganic Biochemistry","volume":"277 ","pages":"Article 113209"},"PeriodicalIF":3.2,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145921997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-31DOI: 10.1016/j.jinorgbio.2025.113210
Alysia J. Kohlbrand , Ryjul W. Stokes , Banumathi Sankaran , Seth M. Cohen
The influenza virus causes a significant burden of illness each year. Although vaccination is the most effective method to prevent seasonal influenza infection, viral escape mechanisms make vaccine composition difficult to predict. Antivirals are crucial for decreasing rates of morbidity and mortality from influenza viral infection. The newest anti-influenza drugs target the RNA-dependent RNA polymerase acidic N-terminal (PAN) endonuclease, a critical component of influenza viral replication machinery. This study examines the structure of inhibitors of PAN that utilize a hydroxypyridinone-based metal-binding pharmacophore (MBP). Specifically, this report explores how the size of substituent groups impacts the binding conformation and affinity of a series of compounds against both wild-type (WT) and resistance mutant strains, I38T and E23K. Co-crystal structures revealed that the distance between compounds and enzyme residue 38 was conserved to maintain strong interactions, resulting in deviations from ideal coordination geometries at the active site metal centers. This suggests the interactions with residue 38 with each compound is important and can impact inhibitor potency as a consequence of distortions in the metal binding geometry of the compounds.
{"title":"Substituent size versus metal binding of inhibitors with variants of influenza endonuclease","authors":"Alysia J. Kohlbrand , Ryjul W. Stokes , Banumathi Sankaran , Seth M. Cohen","doi":"10.1016/j.jinorgbio.2025.113210","DOIUrl":"10.1016/j.jinorgbio.2025.113210","url":null,"abstract":"<div><div>The influenza virus causes a significant burden of illness each year. Although vaccination is the most effective method to prevent seasonal influenza infection, viral escape mechanisms make vaccine composition difficult to predict. Antivirals are crucial for decreasing rates of morbidity and mortality from influenza viral infection. The newest anti-influenza drugs target the RNA-dependent RNA polymerase acidic N-terminal (PA<sub>N</sub>) endonuclease, a critical component of influenza viral replication machinery. This study examines the structure of inhibitors of PA<sub>N</sub> that utilize a hydroxypyridinone-based metal-binding pharmacophore (MBP). Specifically, this report explores how the size of substituent groups impacts the binding conformation and affinity of a series of compounds against both wild-type (WT) and resistance mutant strains, I38T and E23K. Co-crystal structures revealed that the distance between compounds and enzyme residue 38 was conserved to maintain strong interactions, resulting in deviations from ideal coordination geometries at the active site metal centers. This suggests the interactions with residue 38 with each compound is important and can impact inhibitor potency as a consequence of distortions in the metal binding geometry of the compounds.</div></div>","PeriodicalId":364,"journal":{"name":"Journal of Inorganic Biochemistry","volume":"277 ","pages":"Article 113210"},"PeriodicalIF":3.2,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145921996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-30DOI: 10.1016/j.jinorgbio.2025.113208
Tina P. Andrejević , Jakob Kljun , Sanja Matić , Tijana Marković , Žiko Milanović , Kristina Milisavljević , Darko P. Ašanin , Suzana Popović , Dejan Baskić , Iztok Turel , Miloš I. Djuran , Biljana Đ. Glišić
Novel palladium(II), platinum(II), and gold(III) complexes, [PdCl2(py-2tz)] (1), [PtCl2(py-2tz)] (2), and [AuCl2(py-2tz)][AuCl4] (3), py-2tz is 2-(Thiazol-2-yl)pyridine-4,5-dicarboxylate dimethyl ester, were synthesized and characterized using spectroscopy (1H and 13C NMR, IR, and UV–Vis), mass spectrometry, density functional theory (DFT), electrochemical (cyclic voltammetry), and crystallographic methods. Single-crystal X-ray diffraction analysis revealed that all complexes are square-planar with bidentate coordination of the py-2tz ligand via its pyridine and thiazole nitrogen atoms to the corresponding metal ion. These complexes were further evaluated against three human cell lines, two cancer (colon, HCT-116, and cervical adenocarcinoma, HeLa) and one healthy (embryonic lung fibroblast, MRC-5), using the MTT cytotoxicity assay. The influence of these complexes on the type of cell death and cell cycle progression were examined by flow cytometry. Of all the complexes investigated, the gold(III) complex showed the most prominent cytotoxicity toward tumor cells, with reduced toxicity against MRC-5 compared to cisplatin. Furthermore, this complex induced apoptosis and autophagy in both tumor cell lines, and G2/M arrest in HCT-116 cells. The binding interactions of the complexes 1–3 with bovine serum albumin (BSA) and calf thymus DNA (ct-DNA) were also investigated using fluorescence spectroscopy, complemented by molecular docking simulations.
{"title":"Multimodal anticancer potential of newly synthesized palladium(II), platinum(II), and gold(III) complexes with 2-(Thiazol-2-yl)pyridine-4,5-dicarboxylate dimethyl ester","authors":"Tina P. Andrejević , Jakob Kljun , Sanja Matić , Tijana Marković , Žiko Milanović , Kristina Milisavljević , Darko P. Ašanin , Suzana Popović , Dejan Baskić , Iztok Turel , Miloš I. Djuran , Biljana Đ. Glišić","doi":"10.1016/j.jinorgbio.2025.113208","DOIUrl":"10.1016/j.jinorgbio.2025.113208","url":null,"abstract":"<div><div>Novel palladium(II), platinum(II), and gold(III) complexes, [PdCl<sub>2</sub>(py-2tz)] (<strong>1</strong>), [PtCl<sub>2</sub>(py-2tz)] (<strong>2</strong>), and [AuCl<sub>2</sub>(py-2tz)][AuCl<sub>4</sub>] (<strong>3</strong>), py-2tz is 2-(Thiazol-2-yl)pyridine-4,5-dicarboxylate dimethyl ester, were synthesized and characterized using spectroscopy (<sup>1</sup>H and <sup>13</sup>C NMR, IR, and UV–Vis), mass spectrometry, density functional theory (DFT), electrochemical (cyclic voltammetry), and crystallographic methods. Single-crystal X-ray diffraction analysis revealed that all complexes are square-planar with bidentate coordination of the py-2tz ligand <em>via</em> its pyridine and thiazole nitrogen atoms to the corresponding metal ion. These complexes were further evaluated against three human cell lines, two cancer (colon, HCT-116, and cervical adenocarcinoma, HeLa) and one healthy (embryonic lung fibroblast, MRC-5), using the MTT cytotoxicity assay. The influence of these complexes on the type of cell death and cell cycle progression were examined by flow cytometry. Of all the complexes investigated, the gold(III) complex showed the most prominent cytotoxicity toward tumor cells, with reduced toxicity against MRC-5 compared to cisplatin. Furthermore, this complex induced apoptosis and autophagy in both tumor cell lines, and G2/M arrest in HCT-116 cells. The binding interactions of the complexes <strong>1</strong>–<strong>3</strong> with bovine serum albumin (BSA) and calf thymus DNA (ct-DNA) were also investigated using fluorescence spectroscopy, complemented by molecular docking simulations.</div></div>","PeriodicalId":364,"journal":{"name":"Journal of Inorganic Biochemistry","volume":"277 ","pages":"Article 113208"},"PeriodicalIF":3.2,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-29DOI: 10.1016/j.jinorgbio.2025.113206
Haoran Liu , Jingyi Zhang , Yanping Li , Jiamin Jin , Jian Chen , Juzheng Zhang
Although elesclomol (Es) has been investigated as a copper ionophore in antitumor clinical trials, its therapeutic potential remains limited by suboptimal copper transport efficiency and a narrow mechanism of action. To overcome these limitations and improve the anticancer efficacy of copper ionophores, we designed and synthesized L1—a novel chelator capable of forming the binuclear copper complex C1. Our results demonstrate that C1 exhibits superior therapeutic properties compared to Elesclomol–Cu (EsCu), including enhanced cellular copper uptake in gastric cancer cells and multiple anticancer mechanisms. These mechanisms include potent induction of cuproptosis (significantly stronger than EsCu), generation of mitochondrial superoxide and intracellular reactive oxygen species, induction of autophagic lysosome accumulation, DNA damage, and activation of apoptosis. More importantly, in vivo studies revealed a remarkable tumor inhibition rate of 80.3 % for C1, substantially higher than that of EsCu (45 %). These findings establish C1 as a promising next-generation copper-based anticancer agent with enhanced therapeutic potential.
{"title":"Developing a novel binuclear copper complex for enhanced cellular copper uptake and cancer treatment","authors":"Haoran Liu , Jingyi Zhang , Yanping Li , Jiamin Jin , Jian Chen , Juzheng Zhang","doi":"10.1016/j.jinorgbio.2025.113206","DOIUrl":"10.1016/j.jinorgbio.2025.113206","url":null,"abstract":"<div><div>Although elesclomol (Es) has been investigated as a copper ionophore in antitumor clinical trials, its therapeutic potential remains limited by suboptimal copper transport efficiency and a narrow mechanism of action. To overcome these limitations and improve the anticancer efficacy of copper ionophores, we designed and synthesized L1—a novel chelator capable of forming the binuclear copper complex C1. Our results demonstrate that C1 exhibits superior therapeutic properties compared to Elesclomol–Cu (Es<img>Cu), including enhanced cellular copper uptake in gastric cancer cells and multiple anticancer mechanisms. These mechanisms include potent induction of cuproptosis (significantly stronger than Es<img>Cu), generation of mitochondrial superoxide and intracellular reactive oxygen species, induction of autophagic lysosome accumulation, DNA damage, and activation of apoptosis. More importantly, <em>in vivo</em> studies revealed a remarkable tumor inhibition rate of 80.3 % for C1, substantially higher than that of Es<img>Cu (45 %). These findings establish C1 as a promising next-generation copper-based anticancer agent with enhanced therapeutic potential.</div></div>","PeriodicalId":364,"journal":{"name":"Journal of Inorganic Biochemistry","volume":"277 ","pages":"Article 113206"},"PeriodicalIF":3.2,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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