Journal of Inorganic Biochemistry最新文献

This article is a personal chronical of Jim Kincaid's scientific career from his postdoctoral years in my laboratory at Princeton, to his final years in his lab at Marquette. He devoted himself to the study of heme proteins, using Raman spectroscopy as a probe of structure and function, producing many notable advances in our understanding of these key biological molecules. Along the way, Jim supported and encouraged many aspiring scientists. Reminiscences from his students and colleagues affirm his enthusiasm for science and for friendship, his generosity of time and attention, his puckish sense of humor, his unfailing kindness and his concern for the well-being of those around him, to the very end of his life. I was fortunate to have him as a student, collaborator, and life-long friend.

Two Gd(III) complexes [GdL(H₂O)(NO₃)₂(CH₃OH)_0.75(CH₃CH₂OH)_0.25] (Gd1) and [Gd₂(OOCCH₃)₂L₂(H₂O)₆]•2(H₂O) (Gd2) (HL = 2-pyridylcarboxaldehyde isonicotinoylhydrazone) were synthesized with a Schiff base ligand. Crystallographic study reveals both Gd1 and Gd2 have a zero-dimensional mononuclear or binuclear structure. Magnetic investigations demonstrate that Gd1 and Gd2 exhibit potential magnetocaloric effects due to Gd(III) ions, which provide negligible magnetic anisotropy, and possess low-lying excited spin states. The antiproliferative activity of Gd1 and Gd2 to three tumor cell lines was conducted and the results showed Gd1 and Gd2 showed more pronounced antiproliferative activity to A549 cells better than cisplatin. The administration of Gd1 and Gd2 led to an increase in apoptosis among A549 cells in a concentration-dependent manner, along with a corresponding rise in the levels of reactive oxygen species (ROS) within the cells. Besides, Gd1 and Gd2 were able to significantly inhibit tumor cell migration. Cell cycle assay in A549 cells revealed that cell cycle was arrested of G0/G1 phase. Western blotting analysis showed that Gd1 and Gd2 complexes could promote apoptosis in A549 cells by modulating the expression of Bcl-2 and Bax proteins.

Nitric oxide (NO) is a small, short-lived gas molecule that influences various critical functions in living organisms. It involves multiple physiological processes, including cardiovascular function, metabolism, neurotransmission, immunity, and aberrant NO signaling leads to various disorders such as cardiovascular diseases, diabetes, and cancers. In this study, we explored the potential application of copper-nitrite complexes in treating oral precancer and cancer. The copper-nitrite complexes, L₁Cu(NO₂) and L₂Cu(NO₂), were shown to release NO into cells and selectively induce cytotoxicity to oral precancer and cancer cells. Notably, L₁Cu(NO₂) inhibited oral cancer cell proliferation by causing G0/G1 phase cell cycle arrest. Furthermore, L₁Cu(NO₂) induced cell apoptosis and upregulated the expression of p-PRAS40 (proline-rich Akt substrate of 40 kDa) in oral cancer cells. All these results reveal the therapeutic potential of copper-nitrite complexes, especially L₁Cu(NO₂), to be developed as a targeted therapy against oral precancer and cancer.

Developing multifunctional nanomedicines represents a frontier. We have engineered a high-capacity DNA vector basing rolling circle amplification for the delivery of copper sulfide nanoparticles (CuS NPs) and doxorubicin (DOX), coupled with multivalent aptamers (MA) that precisely target tumors, culminating in a multifunctional nanoplatform (RMAL₁Cu@DOX), which combines the chemotherapy (CT)/photothermal therapy (PTT)/chemodynamic therapy (CDT). The vector (RMAL₁) boasts exceptional biocompatibility and incorporates multiple copy units, enabling the precise loading of numerous CuS NPs, forming RMAL₁Cu which possesses a robust photothermal effect and superior Fenton-like catalytic activity, heralding a project of minimally invasive dual-mode (PTT/CDT) therapy. Furthermore, the abundance of G-C of RMAL₁ enabled effective DOX encapsulation through π-π interactions to construct RMAL₁Cu@DOX. The MA integrated into RMAL₁Cu@DOX is pivotal in enhancing the targeting of tumors and in preventing non-specific release of CuS and DOX, enabling an integrated CT/PTT/CDT. Data indicate that 1 nM of RMAL₁Cu could load 270 nM of DOX with an impressive loading capacity of 77 %, and modification with MA, its tumor-targeting ability was amplified by 51-fold and significantly bolstered in vitro imaging outcomes, and the synergistic killing of B16 was as 67.3 %. This innovative nanoplatform offers a comprehensive and holistic strategy for the treatment of malignant tumors.

Due to its commercial availability and well-defined structure, the interaction between bovine protein β-lactoglobulin (βLG) and a wide variety of non-native ligands - including transition metal complexes - has been explored, but its application as an artificial metalloenzyme scaffold is limited. This protein is hypothesized to transport fatty acids and other nutrients during juvenile development, and it binds hydrophobic ligands inside a binding pocket constructed upon an 8-stranded β-barrel, called the 'calyx'. Herein, we compare the binding behavior of two rhenium(anthracene-bispyridine) ('Anth-py₂') tricarbonyl complexes, one with a 12‑carbon chain appended to the ligand scaffold ('^C12Anth-py₂') to βLG. We investigate (i) how calyx-binding specificity is affected by pH (which controls βLG structure at the entrance to the calyx) and (ii) modification of a free cysteine residue located in a putative second binding site of βLG (SMe-βLG). The binding affinities of [Re(^C12Anth-py₂)(CO)₃(solv)]⁺ (ReC₁₂) and [Re(Anth-py₂)(CO)₃(solv)]⁺ (ReCH) for βLG at pH 7.3 were similar at 36 ± 2 μM and 43 ± 1 μM, respectively. The K_D of ReC₁₂ decreased by ∼13 μM at pH 6.1 due to a well-known conformational change (Tanford transition) at the entrance to the calyx; the K_D value was not significantly affected by Cys121 modification, indicating β-barrel calyx binding specificity. In contrast, ReCH experienced a decrease in K_D in response to blocking the second binding (SMe-βLG), but was also unaffected by pH. The results show an increase in binding affinity and specificity as a result of targeted ligand design and utilization of native protein characteristics. The findings will inform and improve the design of future βLG-derived ArMs.

Nitrite (NO₂^-) interacts with myoglobin (Mb) and hemoglobin (Hb) behaving as a ligand of both the ferrous (i.e., Mb(II) and Hb(II)) and ferric (i.e., Mb(III) and Hb(III)) forms. However, while the binding to the Fe(III) species corresponds to the formation of a stable complex (i.e., Mb(III)-NO₂^- and Hb(III)-NO₂^-), in the case of the ferrous forms the reaction proceeds with a nitrite reductase redox process, leading to the oxidation of the heme-protein with the reduction of NO₂^- to NO. This event is of the utmost importance for the rapid production of NO in vivo in the blood stream and in striated muscles, being crucial for the regulation of the blood flow, and thus for O₂ supply to poorly oxygenated tissues, such as the eye's retina. Further, NO₂^- interacts with Mb(II)-O₂ and Hb(II)-O₂, inducing their oxidation with a complex mechanism, which has been only partially elucidated. Mb and Hb form the complex with NO₂^- through the O-nitrito binding mode (i.e., Fe-ONO^-), which is regulated by residues paving the heme distal side; thus, in a site-directed mutant, where HisE7 is substituted by Val, the interaction occurs in the N-nitro binding mode (i.e., Fe-N(O)O^-), like in most other heme-proteins. The structure-function relationships of the interaction of NO₂^- with both ferric and ferrous forms of Mb and Hb are discussed here.

A series of new Pd(II) complexes were synthesized from the reaction of andrographolide appended hydrazide derivatives with potassium tetrachloropalladate K₂[PdCl₄]. The formation of the complexes was confirmed through structural assessments conducted using various spectroscopic techniques. From the spectral studies we confirmed that the ligands coordinated to Pd(II) ion via amine nitrogen and enone oxygen. The complexes were assessed for their antioxidant properties, demonstrating significant radical scavenging activity with a series of free radicals such as 1,1-diphenyl-2-picrylhydrazyl (DPPH^•), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid diammonium salt (ABTS^•+), Super oxide (O^2-) and Nitric oxide (NO^•) radicals compared with standard antioxidants. Moreover, in vitro antiproliferative investigations conducted on A549 (human lung cancer) and HeLa (human cervical cancer) cell lines revealed significant cytotoxicity of the complexes, with lower IC₅₀ values compared to the standard metallo-drug cisplatin. Morphological alterations observed in HeLa and A549 cells when treated with IC₅₀ concentrations of the complexes, as examined through Acridine Orange-Ethidium Bromide (AO-EB) and 4',6-diamidino-2-phenylindole (DAPI) staining techniques, indicated cell death via apoptosis. Biological studies indicated that AGC-Pd exhibited superior activity among others, further the percentages of the apoptotic and necrotic cells were determined by flow cytometric technique.

By introducing new-to-nature transformations, artificial metalloenzymes hold great potential for expanding the biosynthetic toolbox. The chemistry of an active cofactor in these enzymes is highly dependent on how the holoprotein is assembled, potentially limiting the choice of organometallic complexes amenable to incorporation and ability of the protein structure to influence the metal centre. We have previously reported a method utilising ligand exchange as a means to introduce ruthenium-arene fragments into a four-helix bundle protein. In this work we expand the scope of this method to incorporate an iridium pentamethylcyclopentadienyl fragment into a four-helix bundle, yielding an artificial metalloenzyme with improved transfer hydrogenation properties, highlighting that understanding ligand exchange reactions is important for speciation control.

Ovarian cancer represents a leading cause of cancer-related deaths in women worldwide. Chemotherapeutic agents are usually employed to treat the patients, and Ruthenium(II)-based compounds have been investigated as possible substitutes for platinum drugs. In this work, we studied three different Ru(II)-phosphine-mercapto complexes (1-3) as potential cytotoxic agents against A2780 and A2780-cisR ovarian cancer cells. A time-dependent cytotoxicity was observed for 2, which also exhibited better selectivity than cisplatin control. A similar cytotoxic behavior was observed on 3D tumor spheroids. Although no changes were observed in cell cycle distribution, compound 2 affected the mitochondrial membrane potential on A2780 cells, and caused cell death via apoptotic pathway, which was confirmed by flow cytometry assay. Western blotting experiments revealed that 2 affected the expression of p53, PCNA, γH2AX and cleaved caspase-3, making it a promising anticancer agent for ovarian cancer.