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A left‐handed crossover involved in amidohydrolase catalysis
Author(s) -
Miller Maria,
Rao J.K.Mohana,
Wlodawer Alexander,
Gribskov Michael R.
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)80943-o
Subject(s) - amidohydrolase , chemistry , residue (chemistry) , active site , stereochemistry , hydrolase , aspartate carbamoyltransferase , nucleophile , enzyme , threonine , catalysis , hydrolysis , transferase , biochemistry , allosteric regulation , serine
The crystal structure of l ‐asparaginase from Erwinia chrysanthemi in the presence and absence of l ‐aspartate was determined at 1.8 Å resolution. Conserved residues in a left‐handed crossover (a rare occurrence in protein structures) link pairs of dimers into the catalytically active tetrameric form of the enzyme. The structure of ErA containing bound aspartic acid shows that this unusual strand connectivity is an essential part of the active site architecture, responsible for releasing the product of the enzymatic hydrolysis. The orientation of the bound aspartate indicates for the first time a threonine residue as a catalytic nucleophile.