Ficin- and papain-catalyzed reactions. Changes in reactivity of the essential sulfhydryl group in the presence of substrates and competitive inhibitors

Whitaker, John R.

doi:10.1021/bi00839a054

Cited by 27 publications

(12 citation statements)

References 37 publications

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“…An alternative to the model presented above is to postulate that a conformational change occurs when D-or L-BAEE bind to papain (8). Although this is a possible explanation there is no evidence for conformation changes in papain.…”

Section: Resultsmentioning

confidence: 96%

“…The rate of inactivation of papaln by three alkylating reagents was studied at varying concentrations of D-BAEE, a competitive inhibitor of papain (8). The reactions were performed under pseudo-first-order conditions with the inactivator at least tenfold in excess of papain.…”

Section: Resultsmentioning

confidence: 99%

“…Since both D-and L-BAEE completely inhibit the attack of TLCK, they both must occupy at least a part of the site to which TECK binds (or the route by which TLCK must approach the sulfhydryl group). Also D-BAEE is a competitive inhibitor of GEE (8). Hence, both nonproductive sites must overlap a key part of the BGEE binding site, which is a productive site.…”

Section: Resultsmentioning

confidence: 99%

“…l). This conflict has been reconciled by invoking nonproductive binding (3) or a cancellation of effects (8). Inactivation studies in the presence of the competitive inhibitor D-BAEE (g), which does not acylate the enzyme, rather than in the presence of L-BAEE avoid the problem of not howing the k2/k3 ratio (it is zero) and thus simplify the interpretation of the kinetic data on the rates of inactivation of enzyme complexes.…”

Section: Introductionmentioning

confidence: 99%

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Evidence for Nonproductive Binding Subsites within the Active Site of Papain

Glick¹,

Brubacher²

1974

Can. J. Biochem.

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G k k , B. R. & Brubacher, L. J. (1974) Evidence for Nonproductive Binding Subsites within the Active Site of Papain. Cart. J . Biockem. 52,[877][878][879][880][881][882][883] The reactions of several alkylating reagents with the sulfhydryl group in papain have been studied in the presence of varying concentrations of the competitive inhibitor a-N-benzoyl-Darginine ethyl ester. The ratio of the alkylation rate constant of the papain -a-N-benzoylmarginine ethyl ester complex to the rate constant with free papain is 4.3, 1.2, and 0.8 for the alkylating agents 1-chloro-3-tosylamido-4-phenyl-2-butanone, N-ethylmaleimide, and l-chloro-3-tosylamido-7-amino-2-heptanone, respectively. These results are rationalized, along with data for the effect of a-M-benzoyl-L-arginine ethyl ester, in terms of nonproductive binding. Glick, B. W. & Brubacher, L. S. (1974) Evidence for Nonproductive Binding Subsites within the Active Site of Papain. Cm. J. Biochem. 52, 877-883Nous avons ktudik les rkactions de plusieurs agents alkylants avec le groupe sulfhydryle de B a papaine en presence de diverses concentrations d'un inhibiteur compCtitif, l'a-N-benzoyl-Darginine ethyl ester. Le rapport entre la constante du taux dqalky%ation du complexe papainea-N-benzoyl-D-arginine Cthyl ester et la constante du taux d'alkylation de la papaine libre est de 4.3 pour B e l-chloro-3-tosylamido-4-phknyl-2-butan~ne, de 1.2 pour le N-Cthylmalkimide et de 8.0 pour le l-chloro-3-tosylamido-7-amino-2-Reptanone. Ces rksultats, de mCme que I e s donnCes sur l'effet de lqu-M-benzoyl-L-arginine ethyl ester, sont discutCs en termes de liaison nonproductive.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evidence for Nonproductive Binding Subsites within the Active Site of Papain

Glick¹,

Brubacher²

1974

Can. J. Biochem.

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“…At higher glycol concentrations, the binding effect would outgrow the other one, hence the direction reversal of k,. In terms of kinetic mechanism, KM levelling off as well as the reversing of sign of k, could indicate a change between the acylation and the deacylation steps, as the rate-limiting step, a possibility which is likely to occur when those steps are of comparable magnitude (k2 %k3) [24]. On the other hand, DEG binding to the protein may induce conformational changes [25] finally increasing the rate of catalysis.…”

Section: Discussionmentioning

confidence: 99%