Pub Date : 2001-01-01DOI: 10.1080/14756360109162373
L. L. Martins, M. Mourato, A. de Varennes
Aspartate aminotransferase (AAT, EC 2.6.1.1) catalyses the transamination of L-aspartate to oxaloacetate. It has been reported that AAT from different plant sources can catalyse the transamination of other compounds structurally similar to the natural substrates. Specificity and kinetic studies were performed with two aspartate aminotransferase isoenzymes (AAT-1 and AAT-2) from leaves of Lupinus albus L. cv Estoril using different amino donors and acceptors. Both isoenzymes showed residual activity for some of the substrates tested. Competitive inhibition was found with most of the structural analogues which is typical of a ping-pong bi-bi kinetic mechanism. It was found that both isoenzymes can use 2-amino-4-methoxy-4-oxobutanoic acid as amino donor. AAT-2 uses 2-amino-4-methoxy-4-oxobutanoic acid at a similar rate as L-aspartate but AAT-1 uses this substrate at a slower rate. The use of this amino donor by AAT isoenzymes has not been reported previously, and our results indicate structural differences between both isoenzymes.
天冬氨酸转氨酶(AAT, EC 2.6.1.1)催化l -天冬氨酸转氨化成草酰乙酸。据报道，来自不同植物来源的AAT可以催化与天然底物结构相似的其他化合物的转氨作用。采用不同的氨基给体和受体对白Lupinus albus L. cv Estoril叶片的两种天冬氨酸转氨酶同工酶(AAT-1和AAT-2)进行了特异性和动力学研究。这两种同工酶对某些底物都显示出残留活性。大多数结构类似物都存在竞争性抑制，这是典型的乒乓bi-bi动力学机制。结果表明，这两种同工酶均能以2-氨基-4-甲氧基-4-氧丁酸为氨基供体。AAT-2使用2-氨基-4-甲氧基-4-氧丁酸的速率与l -天冬氨酸相似，但AAT-1使用该底物的速率较慢。AAT同工酶使用这种氨基供体以前没有报道过，我们的结果表明两种同工酶之间的结构差异。
{"title":"Effects of Substrate Structural Analogues on the Enzymatic Activities of Aspartate Aminotransferase Isoenzymes","authors":"L. L. Martins, M. Mourato, A. de Varennes","doi":"10.1080/14756360109162373","DOIUrl":"https://doi.org/10.1080/14756360109162373","url":null,"abstract":"Aspartate aminotransferase (AAT, EC 2.6.1.1) catalyses the transamination of L-aspartate to oxaloacetate. It has been reported that AAT from different plant sources can catalyse the transamination of other compounds structurally similar to the natural substrates. Specificity and kinetic studies were performed with two aspartate aminotransferase isoenzymes (AAT-1 and AAT-2) from leaves of Lupinus albus L. cv Estoril using different amino donors and acceptors. Both isoenzymes showed residual activity for some of the substrates tested. Competitive inhibition was found with most of the structural analogues which is typical of a ping-pong bi-bi kinetic mechanism. It was found that both isoenzymes can use 2-amino-4-methoxy-4-oxobutanoic acid as amino donor. AAT-2 uses 2-amino-4-methoxy-4-oxobutanoic acid at a similar rate as L-aspartate but AAT-1 uses this substrate at a slower rate. The use of this amino donor by AAT isoenzymes has not been reported previously, and our results indicate structural differences between both isoenzymes.","PeriodicalId":15776,"journal":{"name":"Journal of enzyme inhibition","volume":"33 1","pages":"251 - 257"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87948111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-01-01DOI: 10.1080/14756360109162389
G. Khodarahmi, C. Laughton, H. Smith, P. Nicholls
The enantioselectivity ratio ((+)-:(-)-forms) of three substituted 1-[(benzofuran-2-yI) phenylmethyl] imidazoles as inhibitors of aromatase (P450AROM) was 2.16, 12.3 and 1.0 for the 4-methyl-, 4-fluoro- and 4-chloro-substituted compounds, respectively. The (±)-compounds were all >1000 times more potent than (±)-aminoglutethimide (IC50 = 12 × 103 nM). High potency (5.3–65.0 nM) for all the enantiomers studied is unusual since activity usually resides in one form for chiral inhibitors of P450AROM- The 4-methyl derivative was fitted into the model [Furet, P., Batzl, C., Bhatnager, A.S., Francotte, E., Rihs, G. and Lang, M. (1993) J. Med. Chem. 36, pp. 1393–1400] for binding of S-(-)-fadrazole to the active site and the (R)- and (S)- forms both gave a good fitting pattern with (S)-(-)-fadrazole so accounting for their close activity. Docking of both forms into the active site model for P450AROM [Laughton, C.A., Zvelebil, M.J.J.M. and Neidel, S. (1993) J. Steroid Biochem. Mol. Biol. 44, pp. 399–407], using the orientation of (S)-(±)-fadrazole, gave similar strong binding along the position of the C and D rings of the steroid substrate and in the hydrophobic cavity below the A/B rings. The site was probed for group size accommodation using the less potent 4-phenyl analogue (IC50(±) = 242nM): the (S)-form showed restricted access to the region under the A ring due to the extended bulk of the biphenyl group.
3个取代的1-[(苯并呋喃-2- yi)苯基甲基]咪唑作为芳香酶抑制剂(P450AROM)的对映选择性比((+)-:(-)-形式)分别为2.16、12.3和1.0。(±)-化合物的效价均大于(±)-氨基卢硫胺的1000倍(IC50 = 12 × 103 nM)。高效(5.3 - -65.0海里)以来所有的对映体的研究是不寻常的活动通常驻留在一个形式的手性抑制剂P450AROM——4-methyl导数是安装到模型[Furet, P . Batzl C, Bhatnager,其子as, Francotte, E,组织,g . Lang, m (1993) j .地中海,化学。36页1393 - 1400)绑定的S - (-) -fadrazole活性部位和(R) - (S) -形式都给了很好的拟合模式与(S) - (-) -fadrazole占他们的亲密活动。两种形式与P450AROM活性位点模型的对接[Laughton, c.a.， Zvelebil, M.J.J.M. and Neidel, S. (1993) J.类固醇生物化学。Mol. Biol. 44, pp. 399-407]，利用(S)-(±)-fadrazole的取向，在类固醇底物的C环和D环以及A/B环下方的疏水腔中产生了类似的强结合。使用较弱的4-苯基类似物(IC50(±)= 242nM)探测该位点的基团大小调节:(S)-形式显示由于联苯基团的扩展而限制进入A环下的区域。
{"title":"Enantioselectivity of Some 1-[(Benzofuran-2-yl) phenylmethyl] imidazoles as Aromatase (P450AROM) Inhibitors","authors":"G. Khodarahmi, C. Laughton, H. Smith, P. Nicholls","doi":"10.1080/14756360109162389","DOIUrl":"https://doi.org/10.1080/14756360109162389","url":null,"abstract":"The enantioselectivity ratio ((+)-:(-)-forms) of three substituted 1-[(benzofuran-2-yI) phenylmethyl] imidazoles as inhibitors of aromatase (P450AROM) was 2.16, 12.3 and 1.0 for the 4-methyl-, 4-fluoro- and 4-chloro-substituted compounds, respectively. The (±)-compounds were all >1000 times more potent than (±)-aminoglutethimide (IC50 = 12 × 103 nM). High potency (5.3–65.0 nM) for all the enantiomers studied is unusual since activity usually resides in one form for chiral inhibitors of P450AROM- The 4-methyl derivative was fitted into the model [Furet, P., Batzl, C., Bhatnager, A.S., Francotte, E., Rihs, G. and Lang, M. (1993) J. Med. Chem. 36, pp. 1393–1400] for binding of S-(-)-fadrazole to the active site and the (R)- and (S)- forms both gave a good fitting pattern with (S)-(-)-fadrazole so accounting for their close activity. Docking of both forms into the active site model for P450AROM [Laughton, C.A., Zvelebil, M.J.J.M. and Neidel, S. (1993) J. Steroid Biochem. Mol. Biol. 44, pp. 399–407], using the orientation of (S)-(±)-fadrazole, gave similar strong binding along the position of the C and D rings of the steroid substrate and in the hydrophobic cavity below the A/B rings. The site was probed for group size accommodation using the less potent 4-phenyl analogue (IC50(±) = 242nM): the (S)-form showed restricted access to the region under the A ring due to the extended bulk of the biphenyl group.","PeriodicalId":15776,"journal":{"name":"Journal of enzyme inhibition","volume":"35 3","pages":"401 - 416"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72593030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-01-01DOI: 10.1080/14756360109162378
S. Streitenberger, J. López-Mas, Á. Sánchez-Ferrer, F. García-Carmona
Lactate oxidase (LOD) was purified from cells of Aerococcus viridans by phase partitioning in Triton X-114 (TX-114), ammonium sulphate fractionation and FPLC ion exchange chromatography. The purification achieved from a crude extract of A. viridans was 32-fold with a 60% recovery of activity. The isolated enzyme was a true FMN-containing LOD in tetrameric form with a subunit molecular weight of 48,000. The KM for L-lactate was 175 μM, a 6-fold less value than described in the literature. Among the inhibitors tested, Cibacron Blue 3GA showed the lowest Ki. At low concentrations, Cibacron Blue 3GA behaved as a dye-, pH- and time-dependent inhibitor. A Dixon plot of the steady-state rate showed the time-dependent inhibition to be non-linear, contrary to that described for other slow-binding inhibitors. A model to explain this phenomenon was proposed. The model implies the binding of Cibacron Blue 3GA to the isomerised form of the initial enzyme-inhibition complex (E'I).
采用Triton X-114 (TX-114)相分割、硫酸铵分离、FPLC离子交换层析等方法纯化了绿色气球菌细胞中的乳酸氧化酶(LOD)。粗提物纯化效果为32倍，活性回收率为60%。分离的酶是一个真正的四聚体形式的含fmn的LOD，亚基分子量为48,000。l -乳酸的KM为175 μM，比文献中描述的值低6倍。在所测试的抑制剂中，Cibacron Blue 3GA的Ki值最低。在低浓度下，Cibacron Blue 3GA表现为染料、pH和时间依赖性抑制剂。稳态速率的Dixon图显示，与其他慢结合抑制剂相反，时间依赖性抑制是非线性的。提出了一个解释这一现象的模型。该模型表明Cibacron Blue 3GA与初始酶抑制复合物(E'I)的异构化形式结合。
{"title":"Non-linear Slow-binding Inhibition of Aerococcus viridans Lactate Oxidase by Cibacron Blue 3GA","authors":"S. Streitenberger, J. López-Mas, Á. Sánchez-Ferrer, F. García-Carmona","doi":"10.1080/14756360109162378","DOIUrl":"https://doi.org/10.1080/14756360109162378","url":null,"abstract":"Lactate oxidase (LOD) was purified from cells of Aerococcus viridans by phase partitioning in Triton X-114 (TX-114), ammonium sulphate fractionation and FPLC ion exchange chromatography. The purification achieved from a crude extract of A. viridans was 32-fold with a 60% recovery of activity. The isolated enzyme was a true FMN-containing LOD in tetrameric form with a subunit molecular weight of 48,000. The KM for L-lactate was 175 μM, a 6-fold less value than described in the literature. Among the inhibitors tested, Cibacron Blue 3GA showed the lowest Ki. At low concentrations, Cibacron Blue 3GA behaved as a dye-, pH- and time-dependent inhibitor. A Dixon plot of the steady-state rate showed the time-dependent inhibition to be non-linear, contrary to that described for other slow-binding inhibitors. A model to explain this phenomenon was proposed. The model implies the binding of Cibacron Blue 3GA to the isomerised form of the initial enzyme-inhibition complex (E'I).","PeriodicalId":15776,"journal":{"name":"Journal of enzyme inhibition","volume":"64 1","pages":"301 - 312"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86207609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The antagonist actions of three sub-series of tetrahydro- β -carbolines at the serotonin 2B (5HT 2B) contractile receptor in the rat stomach fundus are analyzed in relation to the physicochemical properties of the molecules. Significant correlations are obtained between the 5HT 2B receptor antagonist affinity and the hydrophobic, steric, electronic, hydrogen bond acceptor and some indicator variables of substituents. Based on these findings, the mode of actions of these congeneric series and future strategy to synthesize more potential compounds are discussed.
{"title":"Quantitative Structure-Activity Relationship Study on Tetrahydro-β-carboline Antagonists of the Serotonin 2B (5HT 2B) Contractile Receptor in the Rat Stomach Fundus","authors":"P. Singh, Rajesh Kumar","doi":"10.1080/14756360127570","DOIUrl":"https://doi.org/10.1080/14756360127570","url":null,"abstract":"The antagonist actions of three sub-series of tetrahydro- β -carbolines at the serotonin 2B (5HT 2B) contractile receptor in the rat stomach fundus are analyzed in relation to the physicochemical properties of the molecules. Significant correlations are obtained between the 5HT 2B receptor antagonist affinity and the hydrophobic, steric, electronic, hydrogen bond acceptor and some indicator variables of substituents. Based on these findings, the mode of actions of these congeneric series and future strategy to synthesize more potential compounds are discussed.","PeriodicalId":15776,"journal":{"name":"Journal of enzyme inhibition","volume":"1 1","pages":"491 - 497"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89381562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aldose reductase ([EC1.1.1.21]: AR) acts on the first step of the polyol metabolic pathway to catalyze the reduction of glucose to sorbitol with NADPH as a coenzyme. Hyperactivity of the pathway in individuals with high blood glucose level is closely related to the onset or progression of diabetic complications. AR inhibitors have therefore been noted as possible pharmacotherapeutic agents for the treatment of diabetic complications. One AR inhibitor has been on the market in Japan, while some potent inhibitors are in clinical trials. Reviewed are the physiological roles of AR, the chemical structures of AR inhibitors, interactions of AR inhibitors with AR using X-ray studies, and the following potencies of AR inhibitors: in vitro activities for AR, in vitro selectivities between AR and aldehyde reductase, their pharmacological effects in vivo, and their effectiveness in clinical trials. Also discussed are directions for the design of future AR inhibitors.
{"title":"Aldose Reductase Inhibitors","authors":"M. Oka, N. Kato","doi":"10.1080/14756360127568","DOIUrl":"https://doi.org/10.1080/14756360127568","url":null,"abstract":"Aldose reductase ([EC1.1.1.21]: AR) acts on the first step of the polyol metabolic pathway to catalyze the reduction of glucose to sorbitol with NADPH as a coenzyme. Hyperactivity of the pathway in individuals with high blood glucose level is closely related to the onset or progression of diabetic complications. AR inhibitors have therefore been noted as possible pharmacotherapeutic agents for the treatment of diabetic complications. One AR inhibitor has been on the market in Japan, while some potent inhibitors are in clinical trials. Reviewed are the physiological roles of AR, the chemical structures of AR inhibitors, interactions of AR inhibitors with AR using X-ray studies, and the following potencies of AR inhibitors: in vitro activities for AR, in vitro selectivities between AR and aldehyde reductase, their pharmacological effects in vivo, and their effectiveness in clinical trials. Also discussed are directions for the design of future AR inhibitors.","PeriodicalId":15776,"journal":{"name":"Journal of enzyme inhibition","volume":"33 1","pages":"465 - 473"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84151266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-01-01DOI: 10.1080/14756360109162376
G. Taibi, A. Paganini, M. Gueli, F. Ampola, C. Nicotra
Milk xanthine oxidase (xanthine: oxygen oxidore-ductase; XO; EC 1.1.3.22) was found to catalyze the conversion of retinaldehyde to retinoic acid. The ability of XO to synthesize all trans-retinoic acid efficiently was assessed by its turnover number of 31.56 min−1, determined at pH 7.0 with 1nM XO and all trans-retinaldehyde varying between 0.05 to 2μM. The determination of both retinoid and purine content in milk was also considered in order to correlate their concentrations with kinetic parameters of retinaldehyde oxidase activity. The velocity of the reaction was dependent on the isomeric form of the substrate, the all trans- and 9-cis-forms being the preferred substrates rather than 13-cis-retinaldehyde. The enzyme was able to oxidize retinaldehyde in the presence of oxygen with NAD or without NAD addition. In this latter condition the catalytic efficiency of the enzyme was higher. The synthesis of retinoic acid was inhibited 87% and 54% by 4μM and 2μM allopurinol respectively and inhibited 48% by 10 μM xanthine in enzyme assays performed at 2μM all trans-retinaldehyde. The Ki value determined for xanthine as an inhibitor of retinaldehyde oxidase activity was 4 μM.
{"title":"Xanthine Oxidase Catalyzes the Synthesis of Retinoic Acid","authors":"G. Taibi, A. Paganini, M. Gueli, F. Ampola, C. Nicotra","doi":"10.1080/14756360109162376","DOIUrl":"https://doi.org/10.1080/14756360109162376","url":null,"abstract":"Milk xanthine oxidase (xanthine: oxygen oxidore-ductase; XO; EC 1.1.3.22) was found to catalyze the conversion of retinaldehyde to retinoic acid. The ability of XO to synthesize all trans-retinoic acid efficiently was assessed by its turnover number of 31.56 min−1, determined at pH 7.0 with 1nM XO and all trans-retinaldehyde varying between 0.05 to 2μM. The determination of both retinoid and purine content in milk was also considered in order to correlate their concentrations with kinetic parameters of retinaldehyde oxidase activity. The velocity of the reaction was dependent on the isomeric form of the substrate, the all trans- and 9-cis-forms being the preferred substrates rather than 13-cis-retinaldehyde. The enzyme was able to oxidize retinaldehyde in the presence of oxygen with NAD or without NAD addition. In this latter condition the catalytic efficiency of the enzyme was higher. The synthesis of retinoic acid was inhibited 87% and 54% by 4μM and 2μM allopurinol respectively and inhibited 48% by 10 μM xanthine in enzyme assays performed at 2μM all trans-retinaldehyde. The Ki value determined for xanthine as an inhibitor of retinaldehyde oxidase activity was 4 μM.","PeriodicalId":15776,"journal":{"name":"Journal of enzyme inhibition","volume":"104 1","pages":"275 - 285"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79530663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-01-01DOI: 10.1080/14756360109162362
C. Chazalette, M. Rivière-Baudet,, A. Scozzafava, F. Abbate, Zahra Ben Maarouf, C. Supuran
The interaction of human carbonic anhydrase (hCA) isozymes I and II with boron derivatives was investigated by kinetic and spectroscopic studies. These derivatives, tested as new inhibitors of carbonic anhydrase, are sulfonamide and non-sulfonamide boron derivatives and some of them proved to be moderately efficient inhibitors of hCA I and hCA II, their activities being comparable to those of the un-substituted sulfonamides, the classical inhibitors of these zinc enzymes. Ph2BOH, one of the compounds with the highest affinity for hCA II in the present study, has been docked within the active site. After minimisation it was found situated at 7.9 Å from zinc, within the hydrophobic half of the active site, in Van der Waals contacts with the amino acid residues: Val 121, Phe 130, Val 135, Leu 141, Val 143, Val 207 and Pro 201. This is the first time that a CA inhibitor has been found to bind at the edge of the active site cavity, similarly to the CA activator histamine, which binds on the hydrophilic half. This finding may be of importance also for the design of novel types of inhibitors with increased affinity for the different CA isozymes.
用动力学和光谱方法研究了人碳酸酐酶(hCA)同工酶I和II与硼衍生物的相互作用。这些衍生物，作为碳酸酐酶的新抑制剂，被测试为磺胺和非磺胺硼衍生物，其中一些被证明是中度有效的hCA I和hCA II抑制剂，它们的活性与这些锌酶的经典抑制剂未取代的磺胺类化合物相当。Ph2BOH是本研究中对hCA II亲和力最高的化合物之一，已被停靠在活性位点内。最小化后，发现它位于7.9 Å，距离锌，在活性位点的疏水一半内，与氨基酸残基:Val 121, Phe 130, Val 135, Leu 141, Val 143, Val 207和Pro 201进行范德华接触。这是第一次发现CA抑制剂结合在活性位点空腔的边缘，类似于CA激活剂组胺，它结合在亲水性一半。这一发现可能对设计对不同CA同工酶具有更高亲和力的新型抑制剂具有重要意义。
{"title":"Carbonic Anhydrase Inhibitors, Interaction of Boron Derivatives with Isozymes I and II: A New Binding Site for Hydrophobic Inhibitors at the Entrance of the Active Site as shown by Docking Studies","authors":"C. Chazalette, M. Rivière-Baudet,, A. Scozzafava, F. Abbate, Zahra Ben Maarouf, C. Supuran","doi":"10.1080/14756360109162362","DOIUrl":"https://doi.org/10.1080/14756360109162362","url":null,"abstract":"The interaction of human carbonic anhydrase (hCA) isozymes I and II with boron derivatives was investigated by kinetic and spectroscopic studies. These derivatives, tested as new inhibitors of carbonic anhydrase, are sulfonamide and non-sulfonamide boron derivatives and some of them proved to be moderately efficient inhibitors of hCA I and hCA II, their activities being comparable to those of the un-substituted sulfonamides, the classical inhibitors of these zinc enzymes. Ph2BOH, one of the compounds with the highest affinity for hCA II in the present study, has been docked within the active site. After minimisation it was found situated at 7.9 Å from zinc, within the hydrophobic half of the active site, in Van der Waals contacts with the amino acid residues: Val 121, Phe 130, Val 135, Leu 141, Val 143, Val 207 and Pro 201. This is the first time that a CA inhibitor has been found to bind at the edge of the active site cavity, similarly to the CA activator histamine, which binds on the hydrophilic half. This finding may be of importance also for the design of novel types of inhibitors with increased affinity for the different CA isozymes.","PeriodicalId":15776,"journal":{"name":"Journal of enzyme inhibition","volume":"6 1","pages":"125 - 133"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79685814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-01-01DOI: 10.1080/14756360109162352
C. B. Vicentini, M. Guarneri, V. Andrisano, S. Guccione, Thierry Langer, R. Marschhofer, R. Chabin, A. Edison, X. Huang, W. Knight, P. Giori
As a part of an investigation on molecular hybrids as new serine protease inhibitors, the pyrazolo [4,3-c][1,2,5]oxadiazin-3(5H)-one ring system was selected as a model of potential mechanism-based inhibitors. Due to the inherent reactivity of this system an optimal balance between susceptibility to nucleophilic attack and stability in solvents was sought prior to development as therapeutic agents. Substitutions on N5 and C7 of the supporting pyrazole ring with either aliphatic or aromatic groups (compounds 2 a-m) and the replacement of the carbonyl oxygen on the reactive oxadiazinone ring with sulfur (compounds 3a,i) were explored. Two members (2i and 2k) of this class of inhibitors displayed time-dependent inhibition of HLE suggesting mechanism-based inhibition. The observation that HLE generated a product(s) from compound 2i which displayed an identical UV-Visible spectrum to that observed during non-enzymatic hydrolysis further supports this proposal. FlexX-based docking of these compounds into a model of the human leukocyte elastase (HLE) active site produced a molecular model of the inhibitor-enzyme interaction.
{"title":"Potential of Pyrazolooxadiazinone Derivatives as Serine Protease Inhibitors","authors":"C. B. Vicentini, M. Guarneri, V. Andrisano, S. Guccione, Thierry Langer, R. Marschhofer, R. Chabin, A. Edison, X. Huang, W. Knight, P. Giori","doi":"10.1080/14756360109162352","DOIUrl":"https://doi.org/10.1080/14756360109162352","url":null,"abstract":"As a part of an investigation on molecular hybrids as new serine protease inhibitors, the pyrazolo [4,3-c][1,2,5]oxadiazin-3(5H)-one ring system was selected as a model of potential mechanism-based inhibitors. Due to the inherent reactivity of this system an optimal balance between susceptibility to nucleophilic attack and stability in solvents was sought prior to development as therapeutic agents. Substitutions on N5 and C7 of the supporting pyrazole ring with either aliphatic or aromatic groups (compounds 2 a-m) and the replacement of the carbonyl oxygen on the reactive oxadiazinone ring with sulfur (compounds 3a,i) were explored. Two members (2i and 2k) of this class of inhibitors displayed time-dependent inhibition of HLE suggesting mechanism-based inhibition. The observation that HLE generated a product(s) from compound 2i which displayed an identical UV-Visible spectrum to that observed during non-enzymatic hydrolysis further supports this proposal. FlexX-based docking of these compounds into a model of the human leukocyte elastase (HLE) active site produced a molecular model of the inhibitor-enzyme interaction.","PeriodicalId":15776,"journal":{"name":"Journal of enzyme inhibition","volume":"26 1","pages":"15 - 34"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84819595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-01-01DOI: 10.1080/14756360109162387
M. Balbaa, M. Khalifa, M. El-Sabaway, Kamal Kandeelaf
Succinate-cytochrome c reductase (SCR) from mouse liver was inhibited strongly and reversibly by an iron (II) macrocyclic complex 3. The inhibition was observed for the enzyme toward the reduction of both 2,6-dichlorophenol indophenol (DCIP) and cytochrome c (cyt c). The inhibition was a mixed type and noncompetitive with respect to the reduction of DCIP and cyt c, respectively. Values of the inhibition constant ranged from 6.6 to 8.3 μM. The IC50 for the complex 3 was found to be 16.6 × 0.8 and 12.1 × 0.5 μM for the enzyme toward DCIP and cyt c, respectively. The reduced form of complex 3 also exhibited enzyme inhibition but to a less extent. Complex 3, at a lower level, equal to 25% of its LD50 showed about 50% inhibition of the enzyme through in vivo dose-dependent effect. These findings suggested that the structure of the equatorial benzoquinoid macrocyclic ligand of the Fe(II) complex is involved in the enzyme inhibition.
{"title":"Inhibition of Succinate-cytochrome C Reductase by a Ferromacrocyclic Complex","authors":"M. Balbaa, M. Khalifa, M. El-Sabaway, Kamal Kandeelaf","doi":"10.1080/14756360109162387","DOIUrl":"https://doi.org/10.1080/14756360109162387","url":null,"abstract":"Succinate-cytochrome c reductase (SCR) from mouse liver was inhibited strongly and reversibly by an iron (II) macrocyclic complex 3. The inhibition was observed for the enzyme toward the reduction of both 2,6-dichlorophenol indophenol (DCIP) and cytochrome c (cyt c). The inhibition was a mixed type and noncompetitive with respect to the reduction of DCIP and cyt c, respectively. Values of the inhibition constant ranged from 6.6 to 8.3 μM. The IC50 for the complex 3 was found to be 16.6 × 0.8 and 12.1 × 0.5 μM for the enzyme toward DCIP and cyt c, respectively. The reduced form of complex 3 also exhibited enzyme inhibition but to a less extent. Complex 3, at a lower level, equal to 25% of its LD50 showed about 50% inhibition of the enzyme through in vivo dose-dependent effect. These findings suggested that the structure of the equatorial benzoquinoid macrocyclic ligand of the Fe(II) complex is involved in the enzyme inhibition.","PeriodicalId":15776,"journal":{"name":"Journal of enzyme inhibition","volume":"63 1","pages":"381 - 390"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84140213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-01-01DOI: 10.1080/14756360109162366
Ayŝle Dinçler, T. Aydemir
Catalase is a major primary antioxidant defence component that primarily catalyses the decomposition of H2O2 to H2O. Here we report the purification and characterization of catalase from chard (Beta vulgaris var. cicla). Following a procedure that involved chloroform treatment, ammonium sulfate precipitation and three chromatographic steps (CM-cellulose, Sephadex G-25, and Sephadex G-200), catalase was purified about 250-fold to a final specific activity of 56947 U/mg of protein. The molecular weight of the purified catalase and its subunit were determined to be 235000 and 58500 daltons, indicating that the chard catalase is a tetramer. The absorption spectra showed a soret peak at 406 nm, and there was slightly reduction by dithionite. The ratio of absorption at 406 and 275 nanometers was 1.5, the value being similar to that obtained for catalase from other plant sources. In the catalytic reaction, the apparent Km value for chard catalase was 50 mM. The purified protein has a broad pH optimum for catalase activity between 6.0 and 8.0. The enzyme had an optimum reaction temperature at 30 °C. Heme catalase inhibitors, such as azide and cyanide, inhibited the enzyme activity markedly and the enzyme was also inactivated by β-mercaptoethanol, dithiothreitol and iodoacetamide.
{"title":"Purification and Characterization of Catalase from Chard (Beta vulgaris var. cicla)","authors":"Ayŝle Dinçler, T. Aydemir","doi":"10.1080/14756360109162366","DOIUrl":"https://doi.org/10.1080/14756360109162366","url":null,"abstract":"Catalase is a major primary antioxidant defence component that primarily catalyses the decomposition of H2O2 to H2O. Here we report the purification and characterization of catalase from chard (Beta vulgaris var. cicla). Following a procedure that involved chloroform treatment, ammonium sulfate precipitation and three chromatographic steps (CM-cellulose, Sephadex G-25, and Sephadex G-200), catalase was purified about 250-fold to a final specific activity of 56947 U/mg of protein. The molecular weight of the purified catalase and its subunit were determined to be 235000 and 58500 daltons, indicating that the chard catalase is a tetramer. The absorption spectra showed a soret peak at 406 nm, and there was slightly reduction by dithionite. The ratio of absorption at 406 and 275 nanometers was 1.5, the value being similar to that obtained for catalase from other plant sources. In the catalytic reaction, the apparent Km value for chard catalase was 50 mM. The purified protein has a broad pH optimum for catalase activity between 6.0 and 8.0. The enzyme had an optimum reaction temperature at 30 °C. Heme catalase inhibitors, such as azide and cyanide, inhibited the enzyme activity markedly and the enzyme was also inactivated by β-mercaptoethanol, dithiothreitol and iodoacetamide.","PeriodicalId":15776,"journal":{"name":"Journal of enzyme inhibition","volume":"4 1","pages":"165 - 175"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79986460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：