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Structural comparison of Ntn‐hydrolases
Author(s) -
Oin Carita,
Rouvinen Juha
Publication year - 2000
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.9.12.2329
Subject(s) - oxyanion hole , cleave , stereochemistry , enzyme , chemistry , nucleophile , glycoside hydrolase , hydrolase , protein secondary structure , amino acid , peptide sequence , biochemistry , protein structure , catalysis , active site , gene
The Ntn‐hydrolases (N‐terminal nucleophile) are a superfamily of diverse enzymes that has recently been characterized. All of the proteins in this family are activated autocatalytically; they contain an N‐terminally located catalytic nucleophile, and they cleave an amide bond. In the present study, the structures of four enzymes of this superfamily are compared in more detail. Although the amino acid sequence homology is almost completely absent, the enzymes share a similar αββα‐core structure. The central β‐sheets in the core were found to have different packing angles, ranging from 5 to 35°. In the Ntn‐hydrolases under study, eight totally conserved secondary structure units were found (region C). Five of them were observed to contain the greatest number of conserved and functionally important residues and are therefore crucial for the structure and function of Ntn‐hydrolases. Two additional regions, consisting of secondary structure units (regions A and B), were found to be in structurally similar locations, but in different orders in the polypeptide chain. The catalytic machinery is located in the structures in a similar manner, and thus the catalytic mechanisms of all of the enzymes are probably similar. However, the substrate binding and the oxyanion hole differed partially.