R. Gulaboski, Pavlinka Kokoskarova, Sofija Petkovska
: Protein-film voltammetry is recognized as a very efficient tool in mechanistic enzymology, but it is also seen as a relevant approach to gain thermodynamic and kinetic information related to the redox chemistry of many enzymes. This technique requires a small amount of redox enzyme, whose molecules form monomolecular film on the working electrode surface. In this paper we present a simple and time - independent cyclo-voltammetric method for the determination of kinetics of the chemical step of an electrochemical-catalytic (EC’) mechanism in protein- film scenario. Theoretical results of a surface EC’ mechanism show that the limiting cyclo -voltammetric catalytic current, measured at large overpotentials, depends solely on the rate of the chemical regenerative re action. At large overpotentials, the limiting current of the steady-state cyclic voltammograms is independent on all kinetics and thermodynamic parameters related to the electrode reaction of adsorbed enzyme. The approach proposed relies on the dependence of the magnitude of limiting current of the experimental cyclic steady-state voltammograms as a function of the substrate concentration.
{"title":"Time-Independent Methodology to Access Michaelis-Menten Constant by Exploring Electrochemical-Catalytic Mechanism in Protein-Film Cyclic Staircase Voltammetry","authors":"R. Gulaboski, Pavlinka Kokoskarova, Sofija Petkovska","doi":"10.5562/CCA3383","DOIUrl":"https://doi.org/10.5562/CCA3383","url":null,"abstract":": Protein-film voltammetry is recognized as a very efficient tool in mechanistic enzymology, but it is also seen as a relevant approach to gain thermodynamic and kinetic information related to the redox chemistry of many enzymes. This technique requires a small amount of redox enzyme, whose molecules form monomolecular film on the working electrode surface. In this paper we present a simple and time - independent cyclo-voltammetric method for the determination of kinetics of the chemical step of an electrochemical-catalytic (EC’) mechanism in protein- film scenario. Theoretical results of a surface EC’ mechanism show that the limiting cyclo -voltammetric catalytic current, measured at large overpotentials, depends solely on the rate of the chemical regenerative re action. At large overpotentials, the limiting current of the steady-state cyclic voltammograms is independent on all kinetics and thermodynamic parameters related to the electrode reaction of adsorbed enzyme. The approach proposed relies on the dependence of the magnitude of limiting current of the experimental cyclic steady-state voltammograms as a function of the substrate concentration.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2018-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/CCA3383","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45334963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We re-investigated the crystal structure of diaquobis(salicylato)copper(II), CuSal, which is an OD material with disordered layer stacking. The diffraction pattern consists of sharp Bragg spots and diffuse streaks. From the Bragg reflections we determined the ordered part of the structure, which can either be described by an orthorhombic or a twinned monoclinic lattice. The main motif of the structure consists of one-dimensional coordination polymers that are connected by hydrogen bonds into two-dimensional layers. The layer stacking is disordered and from simulation
{"title":"Order-Disorder in Diaquobis(salicylato)copper(II) Revisited","authors":"M. Lutz, Dai, Louiseinfoeu-repo Kroon Batenburg","doi":"10.5562/cca3362","DOIUrl":"https://doi.org/10.5562/cca3362","url":null,"abstract":"We re-investigated the crystal structure of diaquobis(salicylato)copper(II), CuSal, which is an OD material with disordered layer stacking. The diffraction pattern consists of sharp Bragg spots and diffuse streaks. From the Bragg reflections we determined the ordered part of the structure, which can either be described by an orthorhombic or a twinned monoclinic lattice. The main motif of the structure consists of one-dimensional coordination polymers that are connected by hydrogen bonds into two-dimensional layers. The layer stacking is disordered and from simulation","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2018-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45501861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maja Friščić, Maja Štibrić Baglama, M. Milović, K. H. Pilepić, Ž. Maleš
Qualitative phytochemical analyses of eight species from the genus Galium (G. corrudifolium, G. cruciata, G. divaricatum, G. lucidum, G. mollugo, G. palustre, G. parisiense, and G. verum), followed by spectrophotometric evaluation of their total phenolic, flavonoid and iridoid content, as well as antiradical capacity, were conducted. G. cruciata contained the greatest amount of total phenolics (111.00 mg gallic acid equivalents g–1 dry extract), while G. verum had the greatest amount of flavonoids (23.11 mg quercetin equivalents g–1 dry extract) and iridoids (461.30 mg aucubin equivalents g–1 dry extract). The best antioxidant (antiradical) activity was shown by G. cruciata (IC50 (ABTS) = 30.30 µg mL–1; IC50 (DPPH) = 27.62 µg mL–1), followed by G. divaricatum, G. verum and G. palustre. The same species were rich in various bioactive constituents and would be appropriate for inclusion in further investigations considering their biomedical potential. This work is licensed under a Creative Commons Attribution 4.0 International License.
{"title":"Content of Bioactive Constituents and Antioxidant Potential of Galium L. Species","authors":"Maja Friščić, Maja Štibrić Baglama, M. Milović, K. H. Pilepić, Ž. Maleš","doi":"10.5562/CCA3379","DOIUrl":"https://doi.org/10.5562/CCA3379","url":null,"abstract":"Qualitative phytochemical analyses of eight species from the genus Galium (G. corrudifolium, G. cruciata, G. divaricatum, G. lucidum, G. mollugo, G. palustre, G. parisiense, and G. verum), followed by spectrophotometric evaluation of their total phenolic, flavonoid and iridoid content, as well as antiradical capacity, were conducted. G. cruciata contained the greatest amount of total phenolics (111.00 mg gallic acid equivalents g–1 dry extract), while G. verum had the greatest amount of flavonoids (23.11 mg quercetin equivalents g–1 dry extract) and iridoids (461.30 mg aucubin equivalents g–1 dry extract). The best antioxidant (antiradical) activity was shown by G. cruciata (IC50 (ABTS) = 30.30 µg mL–1; IC50 (DPPH) = 27.62 µg mL–1), followed by G. divaricatum, G. verum and G. palustre. The same species were rich in various bioactive constituents and would be appropriate for inclusion in further investigations considering their biomedical potential. \u0000 This work is licensed under a Creative Commons Attribution 4.0 International License.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2018-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/CCA3379","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43023485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Kahrović, A. Zahirović, A. Višnjevac, Irnesa Osmanković, E. Turkušić, H. Kurtagić
Four new heteroleptic copper(II) complexes having chalcone or flavonol ligands and Schiff base (N-phenyl-5-chlorosalicylideneimine) as co-ligand were prepared, chemically and structurally characterized and investigated as functional biomimetic catecholase models. The complexes were prepared by the solution synthesis and crystal and molecular structures were determined by X-ray diffraction. Complexes were chemically characterized by elemental analysis, infrared and electronic absorption spectroscopy as well as by electrochemical measurements. Copper(II) chalcone complexes, with square-pyramidal CuO4N core, are binuclear, featuring phenolate oxygen from the Schiff base as a bridging atom, while copper(II) flavonol complexes are mononuclear, and reveal a square planar CuO3N coordination core. Catalytic activity of the complexes in 3, 5-di-tert-butylcatechol oxidation was confirmed by spectrophotometric and electrochemical measurements. Kinetic measurements revealed that the binuclear (chalcone-containing) complexes have enhanced catalytic activity as compared to the mononuclear Cu(II) flavonol complexes. Relatively high kcat values (300 – 750 h–1) confirmed their respectable biomimetic catecholase-like activity.
{"title":"Chalcone and Flavonol Copper(II) Complexes Containing Schiff Base Co-Ligand: Synthesis, Crystal Structures and Catecholase-like Activity","authors":"E. Kahrović, A. Zahirović, A. Višnjevac, Irnesa Osmanković, E. Turkušić, H. Kurtagić","doi":"10.5562/CCA3334","DOIUrl":"https://doi.org/10.5562/CCA3334","url":null,"abstract":"Four new heteroleptic copper(II) complexes having chalcone or flavonol ligands and Schiff base (N-phenyl-5-chlorosalicylideneimine) as co-ligand were prepared, chemically and structurally characterized and investigated as functional biomimetic catecholase models. The complexes were prepared by the solution synthesis and crystal and molecular structures were determined by X-ray diffraction. Complexes were chemically characterized by elemental analysis, infrared and electronic absorption spectroscopy as well as by electrochemical measurements. Copper(II) chalcone complexes, with square-pyramidal CuO4N core, are binuclear, featuring phenolate oxygen from the Schiff base as a bridging atom, while copper(II) flavonol complexes are mononuclear, and reveal a square planar CuO3N coordination core. Catalytic activity of the complexes in 3, 5-di-tert-butylcatechol oxidation was confirmed by spectrophotometric and electrochemical measurements. Kinetic measurements revealed that the binuclear (chalcone-containing) complexes have enhanced catalytic activity as compared to the mononuclear Cu(II) flavonol complexes. Relatively high kcat values (300 – 750 h–1) confirmed their respectable biomimetic catecholase-like activity.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2018-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49485699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Crystal structure of S-adenosyl-L-homocysteine hydrolase from Cytophaga hutchinsonii in complex with adenosine","authors":"J. Czyrko, M. Jaskólski, K. Brzezinski","doi":"10.2210/PDB6GBN/PDB","DOIUrl":"https://doi.org/10.2210/PDB6GBN/PDB","url":null,"abstract":"","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2018-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68199685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dipeptidyl peptidase III (DPP III) is a zinc- dependent peptidase that cleaves dipeptides off of N-termini of its substrates. Previous studies on human DPP III reveal a reaction mechanism similar to that of thermolysin. Since the active site is conserved within the DPP III family, it is not surprising that the mechanism determined for Bacteroides thetaiotaomicron DPP III (BtDPP III) closely resembles that of hDPP III. However, the hydrogen bond network within the model differs slightly from that in the human ortholog, which results in two proposed pathways. The calculated Gibbs activation energy of 90.1 kJ mol–1 is larger than the one calculated from kinetic data for the preferred substrate Arg2-2-naphthylamide at room temperature (69 kJ mol–1), suggesting the importance of treating the whole DPP III enzyme in the calculations.
{"title":"The Mechanism of Peptide Hydrolysis Catalysed by Dipeptidyl Peptidase III from Bacteroides thetaiotaomicron","authors":"M. Tomin, A. Tomić, B. Kovačević, S. Tomić","doi":"10.5562/CCA3343","DOIUrl":"https://doi.org/10.5562/CCA3343","url":null,"abstract":"Dipeptidyl peptidase III (DPP III) is a zinc- dependent peptidase that cleaves dipeptides off of N-termini of its substrates. Previous studies on human DPP III reveal a reaction mechanism similar to that of thermolysin. Since the active site is conserved within the DPP III family, it is not surprising that the mechanism determined for Bacteroides thetaiotaomicron DPP III (BtDPP III) closely resembles that of hDPP III. However, the hydrogen bond network within the model differs slightly from that in the human ortholog, which results in two proposed pathways. The calculated Gibbs activation energy of 90.1 kJ mol–1 is larger than the one calculated from kinetic data for the preferred substrate Arg2-2-naphthylamide at room temperature (69 kJ mol–1), suggesting the importance of treating the whole DPP III enzyme in the calculations.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2018-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/CCA3343","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43849482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sabina Božič Abram, M. Marušič, M. Živkovič, J. Brčić, J. Plavec
Herein we show how sequences that can form different non-canonical structures affect gene expression levels when inserted in the core of σ70-dependent promoter, between the −35 and −10 elements recognized by RNA polymerase, in E. coli. We note that influence on level of GFP expression varies considerably depending on introduction of non-canonical structural elements in the antisense and sense strands as well as with their propensities to form G-triplex, G-hairpin, hairpin or G-quadruplex structures. Moreover, the extent of repression of expression does not relate to the in vitro thermal stability in a simple manner. Repression is most likely caused by steric interference rather than improper distance between the −35 and −10 elements. Although properties like thermal stability and topology can be somewhat different under in vivo and in vitro conditions, our results suggest that the extent of expression suppression cannot be dependent solely on thermal stabilities of Grich structures alone.
{"title":"Non-canonical Structures in Promoter Modulate Gene Expression in Escherichia coli","authors":"Sabina Božič Abram, M. Marušič, M. Živkovič, J. Brčić, J. Plavec","doi":"10.5562/cca3349","DOIUrl":"https://doi.org/10.5562/cca3349","url":null,"abstract":"Herein we show how sequences that can form different non-canonical structures affect gene expression levels when inserted in the core of σ70-dependent promoter, between the −35 and −10 elements recognized by RNA polymerase, in E. coli. We note that influence on level of GFP expression varies considerably depending on introduction of non-canonical structural elements in the antisense and sense strands as well as with their propensities to form G-triplex, G-hairpin, hairpin or G-quadruplex structures. Moreover, the extent of repression of expression does not relate to the in vitro thermal stability in a simple manner. Repression is most likely caused by steric interference rather than improper distance between the −35 and −10 elements. Although properties like thermal stability and topology can be somewhat different under in vivo and in vitro conditions, our results suggest that the extent of expression suppression cannot be dependent solely on thermal stabilities of Grich structures alone.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2018-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49361033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Three benzamide hydrated derivatives as para-methyl-N-(3-pyridyl)benzamide monohydrate (I) or Mpm ∙ H2O; N-(3-fluorophenyl)-4pyridylcarboxamide monohydrate (II) or NpmF ∙ H2O and para-chloro-N-(3-pyridyl)benzamide dihydrate (III) or Clpm ∙ 2H2O are obtained from a series of crystallization experiments using a range of solvents to obtain polymorphs and solvates (hydrates). Most of the crystallization experiment attempts did not provide hydrates and yielded the starting parent crystalline materials. However, from the experiments, two benzamides, Mpm as a monohydrate and Clpm as a dihydrate were isolated and together with a carboxamide monohydrate as NpmF ∙ H2O are reported herein. The water molecules play a key role in crystal structure formation using classical hydrogen bonding via amide N–H∙∙∙OH2, O– H∙∙∙Npyridine and O–H∙∙∙O=C interactions. They compensate for the excess of strong hydrogen bonding acceptors over donors in the benzamide/pyridinecarboxamide molecules, by participating as O-H hydrogen bond donors twice and usually as an O acceptor once. In the Clpm dihydrate, both water molecules form hydrogen bonded chains along the a-axis direction. The lack of hydrate formation in the majority of related benzamides is presumably related to the relative hydrophobicity of these compounds.
三种苯酰胺水合衍生物对甲基- n -(3-吡啶基)苯酰胺一水合物(I)或Mpm∙H2O;N-(3-氟苯基)-4吡啶基甲酰胺一水合物(II)或NpmF∙H2O和对氯-N-(3-吡啶基)苯酰胺二水合物(III)或Clpm∙2H2O是通过一系列结晶实验得到的，使用一系列溶剂获得多晶型和溶剂化物(水合物)。大多数结晶实验都没有提供水合物，只能得到起始母晶材料。然而，从实验中分离出两种苯酰胺，一水合的Mpm和二水合的Clpm，并与一水合的carboxamide一起作为NpmF∙H2O。水分子通过酰胺N-H∙∙∙OH2、O - H∙∙Npyridine和O - H∙∙O=C相互作用，利用经典氢键在晶体结构形成中发挥关键作用。它们补偿了苯酰胺/吡啶甲酰胺分子中强氢键受体多于给体的情况，它们作为O- h氢键给体参与两次，通常作为O受体参与一次。在二水合物Clpm中，两个水分子沿着a轴方向形成氢键链。在大多数相关的苯酰胺中缺乏水合物的形成可能与这些化合物的相对疏水性有关。
{"title":"Aggregation in Three Benzamide or Pyridylcarboxamide Hydrates: Formation of 1D Chains Comprising Water Molecules in a Chloro(pyridyl)benzamide Dihydrate","authors":"P. Mocilac, J. Gallagher, C. Jelsch","doi":"10.5562/CCA3347","DOIUrl":"https://doi.org/10.5562/CCA3347","url":null,"abstract":"Three benzamide hydrated derivatives as para-methyl-N-(3-pyridyl)benzamide monohydrate (I) or Mpm ∙ H2O; N-(3-fluorophenyl)-4pyridylcarboxamide monohydrate (II) or NpmF ∙ H2O and para-chloro-N-(3-pyridyl)benzamide dihydrate (III) or Clpm ∙ 2H2O are obtained from a series of crystallization experiments using a range of solvents to obtain polymorphs and solvates (hydrates). Most of the crystallization experiment attempts did not provide hydrates and yielded the starting parent crystalline materials. However, from the experiments, two benzamides, Mpm as a monohydrate and Clpm as a dihydrate were isolated and together with a carboxamide monohydrate as NpmF ∙ H2O are reported herein. The water molecules play a key role in crystal structure formation using classical hydrogen bonding via amide N–H∙∙∙OH2, O– H∙∙∙Npyridine and O–H∙∙∙O=C interactions. They compensate for the excess of strong hydrogen bonding acceptors over donors in the benzamide/pyridinecarboxamide molecules, by participating as O-H hydrogen bond donors twice and usually as an O acceptor once. In the Clpm dihydrate, both water molecules form hydrogen bonded chains along the a-axis direction. The lack of hydrate formation in the majority of related benzamides is presumably related to the relative hydrophobicity of these compounds.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2018-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/CCA3347","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45613352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Wood, Clare A Tovee, Andrew G. P. Maloney, S. Ward
There is a long history of chemical crystallography and use of the Cambridge Structural Database (CSD) in Croatia, which dates back to 1985 when the CSD first became accessible there thanks to the efforts of Biserka Kojić-Prodić as head of the National Affiliated Centre. On the occasion of Dr Kojić-Prodić’s 80th birthday we take the opportunity to look back at the history of crystallography in Croatia, and particularly in Biserka’s career, from the point of view of the CSD. Biserka has been a prolific author and contributor of crystal structures over the years sharing over 400 structures and collaborating with over 270 different co-authors on a wide range of different types of structure.
{"title":"A Historical Perspective on Crystallography in Croatia and the Career of Biserka Kojić-Prodić from the Viewpoint of the CSD","authors":"P. Wood, Clare A Tovee, Andrew G. P. Maloney, S. Ward","doi":"10.5562/CCA3342","DOIUrl":"https://doi.org/10.5562/CCA3342","url":null,"abstract":"There is a long history of chemical crystallography and use of the Cambridge Structural Database (CSD) in Croatia, which dates back to 1985 when the CSD first became accessible there thanks to the efforts of Biserka Kojić-Prodić as head of the National Affiliated Centre. On the occasion of Dr Kojić-Prodić’s 80th birthday we take the opportunity to look back at the history of crystallography in Croatia, and particularly in Biserka’s career, from the point of view of the CSD. Biserka has been a prolific author and contributor of crystal structures over the years sharing over 400 structures and collaborating with over 270 different co-authors on a wide range of different types of structure.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2018-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47546941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marta Bošnjaković, Ivana Leščić Ašler, Z. Štefanić
Purine nucleoside phosphorylase (PNP) is an essential enzyme in the purine salvage pathway of Helicobacter pylori. Since H. pylori lacks the ability to synthesize purine nucleosides de novo, inhibition of this enzyme could stop the growth of this bacterium. However, for the design of successful inhibitors the details of the mechanism of this enzyme should be fully understood. PNPs catalyze cleavage of the glycosidic bond of purine nucleosides, and phosphate is one of the substrates. It is thought that binding of phosphate induces the conformational change as a necessary initial step in the catalysis. This conformational change is manifested in closing of either one of the six active sites in the homohexameric PNPs. It is unclear whether the binding of phosphate is sufficient or just a necessary condition for the closing of the active site. In this paper we conducted an experiment to check this by soaking the crystals of the apo form of the enzyme in increasing concentrations of phosphate.
{"title":"The Role of Phosphate Binding in Purine Nucleoside Phosphorylase of Helicobacter pylori","authors":"Marta Bošnjaković, Ivana Leščić Ašler, Z. Štefanić","doi":"10.5562/CCA3335","DOIUrl":"https://doi.org/10.5562/CCA3335","url":null,"abstract":"Purine nucleoside phosphorylase (PNP) is an essential enzyme in the purine salvage pathway of Helicobacter pylori. Since H. pylori lacks the ability to synthesize purine nucleosides de novo, inhibition of this enzyme could stop the growth of this bacterium. However, for the design of successful inhibitors the details of the mechanism of this enzyme should be fully understood. PNPs catalyze cleavage of the glycosidic bond of purine nucleosides, and phosphate is one of the substrates. It is thought that binding of phosphate induces the conformational change as a necessary initial step in the catalysis. This conformational change is manifested in closing of either one of the six active sites in the homohexameric PNPs. It is unclear whether the binding of phosphate is sufficient or just a necessary condition for the closing of the active site. In this paper we conducted an experiment to check this by soaking the crystals of the apo form of the enzyme in increasing concentrations of phosphate.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2018-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49079381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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