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ζ‐Crystallin versus other members of the alcohol dehydrogenase super‐family Variability as a functional characteristic
Author(s) -
Jörnvall Hans,
Persson Bengt,
Du Bois Garrett C.,
Lavers Gene C.,
Chen John H.,
Gonzalez Pedro,
Rao P.Vasantha,
Zigler J.Samuel
Publication year - 1993
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(93)81578-n
Subject(s) - alcohol dehydrogenase , sorbitol dehydrogenase , crystallin , dehydrogenase , enzyme , biochemistry , sorbitol , biology , alcohol oxidoreductase , chemistry , alcohol , stereochemistry , biophysics , nad+ kinase
Species variability of the lens protein ζ‐crystallin was correlated with those of alcohol dehydrogenases of classes I and III and sorbitol dehydrogenase in the same protein family. The extent of overall variability, nature of residues conserved, and patterns of segment variability, all fall within the limits typical of the ‘variable’ group of medium‐chain alcohol dehydrogenases. This shows that ζ‐crystallin is subject to restrictions similar to those of classical liver alcohol dehydrogenase and therefore derived from a metabolically active enzyme like other enzyme crystalline. Special residues at the active site, however, differ substantially, including an apparent lack of a zinc‐binding site. This is compatible with altered functional properties and makes the spread within this medium‐chain dehydrogenase family resemble the wide spread within the short‐chain dehydrogenases. Schematic plotting is useful for illustrating the differences between ‘variable’ and ‘constant’ enzymes.