The nature and reactivity of the 'essential' thiol in rabbit muscle creatine kinase III (EC 2.7.3.2)

Fawcett A.H., Keto A.I., Mackerras P., Hamilton S.E. and Zerner B. (1982) The nature and reactivity of the 'essential' thiol in rabbit muscle creatine kinase III (EC 2.7.3.2). Biochemical and Biophysical Research Communications, 107 1: 302-306. doi:10.1016/0006-291X(82)91704-1


Author Fawcett A.H.
Keto A.I.
Mackerras P.
Hamilton S.E.
Zerner B.
Title The nature and reactivity of the 'essential' thiol in rabbit muscle creatine kinase III (EC 2.7.3.2)
Journal name Biochemical and Biophysical Research Communications   Check publisher's open access policy
ISSN 1090-2104
Publication date 1982-07-16
Sub-type Article (original research)
DOI 10.1016/0006-291X(82)91704-1
Volume 107
Issue 1
Start page 302
End page 306
Total pages 5
Subject 1303 Specialist Studies in Education
1304 Biophysics
1312 Molecular Biology
Abstract Rabbit muscle creatine kinase III (EC 2.7.3.2) can be reacted with 2-chloromercuri-4-nitrophenol and this results in the incorporation of two moles of mercurial per mole of enzyme subunit in a biphasic reaction. The second-order rate constant for the slow reaction is 475 ± 42 M-1 s-1. S-Carboxamidomethyl-creatine kinase reacts with a single mole of mercurial per mole of subunit. The rate constant, 466 ± 57 M-1 s-1, is almost identical to that for the slow reaction of the native enzyme. The reaction between 3-carboxy-4-nitrophenylthio-creatine kinase and 2-chloromercuri-4-nitrophenol has a second-order rate constant of 449 ± 56 M-1 s-1. The results may be explained if the mercurial reacts very rapidly with that cysteine residue which reacts independently with iodoacetamide or 5,5′-dithiobis(2-nitrobenzoic acid). However, 2-chloromercuri-4-nitrophenol also reacts more slowly with a second cysteine residue. Definition of the essentiality of thiol groups in enzymes by reaction with labile ligands, here represented by organomercurials, clearly must be approached with caution.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import
 
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