Benzoylamidoacetonitrile is bound as a thioimidate in the active site of papain: J.Biol.Chem.

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TypeArticle
Journal titleJ.Biol.Chem.
Volume261
Issue20
Pages90879089; # of pages: 3
Subject13C; 13C-NMR; Acetonitriles; ACTIVE-SITE; Binding Sites; chemistry; Cysteine; ENZYME; Form; FORMS; Imidoesters; INTERMEDIATE; Magnetic Resonance Spectroscopy; metabolism; MODEL; Nitrogen; NMR; NMR spectroscopy; NMR-spectroscopy; Papain; SITE; SPECTROSCOPY; STATE; structure; Sulfhydryl Compounds; TRANSITION
Abstract13C NMR spectroscopy has been used to demonstrate that 13CN-labeled benzoylamidoacetonitrile forms a covalent adduct with the thiol group of cysteine 25 in the active site of papain. Spectral comparison with model compounds indicates that the adduct is a thioimidate. On the basis of a proposed mechanism for the formation of the thioimidate, it is concluded that the -CH2C(= NH)S--imino nitrogen does not sit in the active site in the same manner as the thiol ester carbonyl oxygen of the thiol acyl enzyme (or the oxyanion of the tetrahedral intermediate). Thus, in this sense the stabilization of the thioimidate does not reflect a similarity in structure between the bound thioimidate and the transition state
Publication date
LanguageEnglish
AffiliationNRC Institute for Biological Sciences; National Research Council Canada
Peer reviewedNo
NRC numberBRISSON1986B
NPARC number9382890
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Record identifier3c5f2bba-6b71-41ae-8050-0113804106fb
Record created2009-07-10
Record modified2016-05-09
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