Diazomethyl ketone substrate derivatives as active-site-directed inhibitors of thiol proteases. Papain. 1977

R Leary, and D Larsen, and H Watanabe, and E Shaw

The diazomethyl ketones of z-Phe-Phe inactivate papain by a stoichiometric reaction at the active-center thiol. Since the reagents are stable in mercaptoethanol, their reaction with papain is judged to be the result of complex formation characteristic of affinity-labeling reagents. The diazomethyl ketones react by a mechanism different from that of chloromethyl ketones, since the pH dependence of their inactivation of papain is different, the rate increasing with decreasing pH. This relationship has been observed in other cases, such as in the reaction of azaserine with glutamine amidotransferases [Buchanan, J. M. (1973), Adv. Enzmol. Relat. Areas Mol. Biol. 39, 91], and is interpreted as an indication of reaction with a thiol group in its protonated form.

UI MeSH Term Description Entries
D007659 Ketones Organic compounds containing a carbonyl group Ketone
D007700 Kinetics The rate dynamics in chemical or physical systems.
D010206 Papain A proteolytic enzyme obtained from Carica papaya. It is also the name used for a purified mixture of papain and CHYMOPAPAIN that is used as a topical enzymatic debriding agent. EC 3.4.22.2. Tromasin
D010649 Phenylalanine An essential aromatic amino acid that is a precursor of MELANIN; DOPAMINE; noradrenalin (NOREPINEPHRINE), and THYROXINE. Endorphenyl,L-Phenylalanine,Phenylalanine, L-Isomer,L-Isomer Phenylalanine,Phenylalanine, L Isomer
D003978 Diazomethane A diazonium compound with the formula CH2N2. Diazirine
D000345 Affinity Labels Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors. These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids. Affinity Labeling Reagents,Labeling Reagents, Affinity,Labels, Affinity,Reagents, Affinity Labeling
D001665 Binding Sites The parts of a macromolecule that directly participate in its specific combination with another molecule. Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D013329 Structure-Activity Relationship The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups. Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships

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