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Closely related isozymes of alcohol dehydrogenase Carboxymethylation: γ 1 γ 1 differs widely from both β 1 β 1 and its equine equivalence EE
Author(s) -
Johansson Jan,
Vallee Bert L.,
Jörnvall Hans
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)80265-5
Subject(s) - isozyme , chemistry , imidazole , histidine , alcohol dehydrogenase , alcohol , reactivity (psychology) , stereochemistry , active site , dehydrogenase , enzyme , biochemistry , alternative medicine , pathology , medicine
Human γ 1 γ 1 alcohol dehydrogenase is quite insensitive to inactivation by iodoacetate, its equine counterpart EE highly sensitive, and the human β 1 β 1 form intermediately sensitive. Imidazole hardly influences the iodoacetate inactivation of γ 1 γ 1 , enhances that of EE and decreases that of β 1 β 1 . In all isozymes metal‐binding Cys residues are the most reactive, but the patterns for those binding the active site zinc atom differ. In phosphate, Cys‐46 is most sensitive in EE and γ 1 γ 1 , Cys‐174 in β 1 β 1 . This difference appears to correlate with the absence or presence, respectively, of an extra methyl group in the side‐chain at position 48 (Ser in EE and γ 1 γ 1 , Thr in β 1 β 1 ). In imidazole, the reactivity in β 1 β 1 is shifted to Cys‐46, while the specificity is enhanced in EE and decreased in γ 1 γ 1 . Thus, the inactivations illustrate large defferences among structures closely related.