1qi3
From Proteopedia
|
MUTANT (D193N) MALTOTETRAOSE-FORMING EXO-AMYLASE IN COMPLEX WITH MALTOTETRAOSE
Overview
The crystal structures of the four product-complexed single mutants of the, catalytic residues of Pseudomonas stutzeri maltotetraose-forming, alpha-amylase, E219G, D193N, D193G and D294N, have been determined., Possible roles of the catalytic residues Glu219, Asp193 and Asp294 have, been discussed by comparing the structures among the previously determined, complexed mutant E219Q and the present mutant enzymes. The results, suggested that Asp193 predominantly works as the base catalyst, (nucleophile), whose side chain atom lies in close proximity to the, C1-atom of Glc4, being involved in the intermediate formation in the, hydrolysis reaction. While Asp294 works for tightly binding the substrate, to give a twisted and a deformed conformation of the glucose ring at, position -1 (Glc4). The hydrogen bond between the side chain atom of, Glu219 and the O1-atom of Glc4, that implies the possibility of, interaction via hydrogen, consistently present throughout these analyses, supports the generally accepted role of this residue as the acid catalyst, (proton donor).
About this Structure
1QI3 is a Single protein structure of sequence from Pseudomonas stutzeri with CA and MTT as ligands. Active as Glucan 1,4-alpha-maltotetraohydrolase, with EC number 3.2.1.60 Full crystallographic information is available from OCA.
Reference
Roles of catalytic residues in alpha-amylases as evidenced by the structures of the product-complexed mutants of a maltotetraose-forming amylase., Hasegawa K, Kubota M, Matsuura Y, Protein Eng. 1999 Oct;12(10):819-24. PMID:10556241
Page seeded by OCA on Wed Nov 21 00:43:47 2007
