Reversible Inhibition of the Esterase Activity of Carboxypeptidase A by Carboxylate Anions

Bunting, John W.; Myers, Chester D.

doi:10.1139/v73-400

Cited by 18 publications

(23 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The influence of R on substrate binding might be ascribed, therefore, to varying degrees of hydrophobic interac4As discussed in the Results section, the parameters for this ester were obtained by a less satisfactory method than for the other esters listed in Table 1 tion between the substrate and the enzvme. The importance of hydrophobic interaction between the enzyme and inhibitor anions has been demonstrated in our laboratory (21,22) by showing that inhibition constants for the binding of RC0,-and RCH(C0,-), which are competitive inhibitors of the hydrolysis of 1: R = CH,C6H5 by carboxypeptidase A are linearly correlated with Hansch's n parameter (34,35), provided the hydrophobic moiety of the inhibitor does not become too large.…”

Section: Discussionmentioning

confidence: 96%

“…Firstly, we felt that it should be possible to quantitatively interpret substrate inhibition for the previously studied 1 : R = C6H, and 1 : R = CH,C6H5 and other hippuric acid esters by a common mechanism. Secondly, we hoped to define the specificity of carboxypeptidase A with respect to the alcohol moiety of ester substrates, and compare this specificity with recent studies in our laboratory (21,22) on the reversible binding of carboxylate anion inhibitors to this enzyme, and with the limited available data on the specificity of this enzyme for peptide substrates.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Substrate Inhibition in the Hydrolysis of Hippuric Acid Esters by Carboxypeptidase A

Murphy¹,

Bunting²

1975

Can. J. Chem.

Self Cite

View full text Add to dashboard Cite

. Can. J. Chem. 53,283 (1975). The dependence of initial velocity upon substrate concentration has been examined in the carboxypeptidase A catalyzed hydrolysis of the following hippuric acid esters (at pH 7.5, 25", ionic strength0.5): C6H5CONHCH,C0,CHRC0,H: R = CH,; CH,CH,;(CH,~CH,; (CH,),CH,; (CH,),CH,; CH(CH,),; CH,CH(CH,),; C6H,; CH,C6H5. All of these esters d~splay marked substrate inhibition of their enzymic hydrolyses. With the exception of R = CH,, the velocitysubstrate concentration profiles for each of these esters can be rationalized by the formationof an E.S, complex which, independent of the alcohol moiety of the ester, reacts approximately 25 times more slowly than the E.S complex. For most of these esters, the formation of E.S, approximates ordered binding of the substrate molecules at the catalytic and inhibitory sites. While binding at the catalytic site is markedly dependent on the nature of the R group, binding of a second substrate molecule to E.S is not significantly affected by the nature of the R side chain. For R = C6H5, the D ester is neither a substrate nor a competitive inhibitor of the hydrolysisofthe L-ester but can replace the L-esterat the binding site which is responsible for substrate inhibition. The kinetic analysis suggests that this behavior of D-and L-enantiomers is also typical of theother esters examined (except possibly R = CH,). For R = CH, only, substrate activation also seems to occur prior to the onset of substrate inhibition at higher substrate concentrations. En faisant exception du cas oh R = CH,, tous les profils de la vitesse par rapport a la concentration de substrat, pour chacun de ces esters, peuvent &tre rationalises par la formation I I d'un complexe E.S2 qui, indipendant de la portion alcoolique de l'ester, reagit environ 25 fois moins rapidement que le complexe E.S. Pour la plupart de ces esters, la formation des 1 complexes E.S2 est approximativement parallele avec la liaison ordonnee des moltcules de substrat aux sites catalytique et inhibiteur. Alors que la liaison a u site catalytique depend d'une facon importante sur la nature du groupe R, la liaison d'une deuxierne moltcule de substrat au complexe E.S n'est pas effectee d'une rnaniere importante par la nature de la chaine laterale R. Pour R = C6Hs, I'ester D n'est ni un substrat ni un inhibiteur competitif de l'hydrolyse de I'ester L mais peut rernplacer I'ester L au site de liaison qui est responsable pour l'inhibition du substrat. L'analyse de la cinktique suggere que la facon de rkagir des enantiomeres D et L est aussi typique des autres esters examines (a I'exception possiblement de R = CH3). Dans le cas particulier oh R = CH,, l'activation du substrat semble aussi se produire avant l'apparition de I'inhibition du substrat i des concentrations de substrat plus tlevees.[Traduit par le journal]The hydrolysis of many ester and peptide sub- For personal use only.

show abstract

Section: Discussionmentioning

confidence: 96%

mentioning

confidence: 99%

Substrate Inhibition in the Hydrolysis of Hippuric Acid Esters by Carboxypeptidase A

Murphy¹,

Bunting²

1975

Can. J. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…6 assuming noncompetitive inhibition gives a Ki value which appears to decrease with increasing inhibitor concentration ( uptake or release of protons at p H 7.5. While this fact makes it impossible to study amide nominally competitive inhibitors but which hydrolysis on the pH-stat at pH 7.5, it may be also show a linear dependence of E/v on I2 taken advantage of to study the reversible (2,3,10). This partially competitive inhibition inhibition of ester hydrolysis by amide subhas been shown to be consistent with the forma-strates.…”

Section: Resultsmentioning

confidence: 99%

“…All experimental techniques and data treatment were as previously described (1,2). For the uninhibited reaction under these conditions K,,, = 7.2 x M and kc,, = 2.50 x lo4 min-' (1).…”

Section: Methodsmentioning

confidence: 99%

“…Recent studies (1)(2)(3) in our laboratory of the reversible inhibition of the hydrolysis of O-hippuryl-L-3-phenyllactic acid by bovine carboxypeptidase A have revealed a variety of competitive, partially competitive, and noncompetitive modes of inhibition by carboxylate anions. The form of inhibition appears to be very dependent on the size and structure of the hydrophobic unit of the inhibiting anion.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Reversible Inhibition of Carboxypeptidase A. IV. Inhibition of Specific Esterase Activity by Hippuric Acid and Related Species and other Amino Acid Derivatives and a Comparison with Substrate Inhibition

Bunting¹,

Myers²

1975

Can. J. Chem.

Self Cite

View full text Add to dashboard Cite

. Can. J. Chem. 53,1993Chem. 53, (1975. The anions of each of the following carboxylic acids exhibit uncompetitive inhibition of the hydrolysis of 0-hippuryl-L-3-phenyllactic acid by bovine carboxypeptidase A at p H 7.5, 25", ionic strength 0.2: hippuric acid, p-chloro-and p-nitrohippuric acids, hippurylglycine, carbobenzoxyglycine, phenaceturic acid, N-(3-phenylpropanoyl)glycine, benzoxyacetic acid, 3-benzoylpropanoic acid, and 0-hippuryl-D-mandelic acid. In each case, this uncompetitive inhibition is consistent with the ordered binding of substrate and inhibitor to the enzyme; i.e. the inhibitor binds to E.S but not to the free enzyme. Evidence is presented for the binding site for uncompetitive inhibitors being the same as for inhibitory ester substrate molecules. Comparison of the specificities of uncompetitive inhibitors and esters which display substrate inhibition provides evidence for a critical conformational change which controls the binding of uncompetitive inhibitors and inhibitory substrate molecules.D-Phenylalanine, D-leucine, D-p-nitrophenylalanine, glycyl-L-tyrosine, glycyl-L-phenylalanine, and glycyl-L-leucine are competitive inhibitors of the enzymic hydrolysis of 0-hippuryl-L-3-phenyllactic acid, whereas the N-chloroacetyl derivatives of L-tyrosine, L-phenylalanine, and L-leucine are noncompetitive inhibitors. For the above D-amino acids, glycyl dipeptides, and N-chloroacetyl amino acids, the phenylalanine derivative in each case is a considerably stronger inhibitor than the corresponding leucine derivative. This preference is similar to that observed for the binding of peptide substrates but the reverse of that observed for ester substrates and simple mono-and dicarboxylate ion inhibitors.The peptide substrates carbobenzoxyglycylglycyl-L-phenylalanine and N-chloroacetyl-Lphenylalanine are noncompetitive inhibitors of the enzymic hydrolysis of 0-hippuryl-L-3-phenyllactic acid. This clearly demonstrates the presence of different ester and peptide binding sites in this enzyme, which is consistent with conclusions from recent studies in other laboratories. JOHN W. BUNTING et CHESTER D. MYERS. Can. J. Chem. 53,1993Chem. 53, (1975. A un p H de 7.5, une tempkrature de 25" et une force ionique de 0.2, les anions de chacun des acides carboxyliques suivants agissent comme inhibiteurs incompktitifs pour l'hydrolyse de I'acide 0-hippuryl L-phknyl-3 lactique par la carboxypeptidase A du boeuf: l'acide hippurique, les acides p-chloro-et p-nitrohippuriques, la hippurylglycine, la carbobenzoxyglycine, I'acide phknaceturique, la N-(phknyl-3 propanoyl) glycine, l'acide benzoxyacktique, I'acide benzoyl-3 propanoi'que et I'acide 0-hippuryl D-mandelique. Dans chaque cas, cette inhibition incompttitive est en accord avec une association ordonnke du substrat et de I'inhibiteur a l'enzyme; i.e. I'inhibiteur s'associe au E.S mais non a l'enzyme libre. On presente des resultats suggkrant que le site d'association des inhibiteurs incompktitifs est le mCme que le site pour les molkcules d'esters agissant comme substra...

show abstract

Synthesis, Structure, and Properties of Azatriangulenium Salts

2001

View full text Add to dashboard Cite

A general synthetic route to novel nitrogen-bridged heterocyclic carbenium ions of the acridinium and triangulenium type has been developed and investigated. The synthetic method is based on nucleophilic aromatic substitution (SNAr) on the tris(2,6-dimethoxyphenyl)carbenium ion (1) with primary amines and, by virtue of its stepwise and irreversible nature, provides a powerful tool for the preparation of a wide variety of new heterocyclic carbenium salts. Several derivatives of the three new oxygen- and/or nitrogen-bridged triangulenium salts, azadioxa- (6), diazaoxa- (7), and triazatriangulenium (4), have been synthesized and their physicochemical properties have been investigated. Crystal structures for compounds 2 b-PF6, 2 d-PF6, 4b-BF4, 4c-BF4, 6e-BF4, and 8 are reported. The different packing modes found for the triazatriagulenium salts are discussed in relation to the electrostatic and space-filling requirements of the ions. The stabilities of the cations 6a, 7b, and 4a, as expressed by their pKR+ values, have been determined in strongly basic nonaqueous solution by use of the C_ acidity function; the values obtained were 14.5, 19.4, and 23.7, respectively. This study further implied that the C_ scale in its present form is unsuitable for the precise determination of pKR+ values beyond 22.

show abstract

Reversible Inhibition of the Esterase Activity of Carboxypeptidase A by Carboxylate Anions

Cited by 18 publications

References 24 publications

Substrate Inhibition in the Hydrolysis of Hippuric Acid Esters by Carboxypeptidase A

Substrate Inhibition in the Hydrolysis of Hippuric Acid Esters by Carboxypeptidase A

Reversible Inhibition of Carboxypeptidase A. IV. Inhibition of Specific Esterase Activity by Hippuric Acid and Related Species and other Amino Acid Derivatives and a Comparison with Substrate Inhibition

Synthesis, Structure, and Properties of Azatriangulenium Salts

Contact Info

Product

Resources

About