1jda
From Proteopedia
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MALTOTETRAOSE-FORMING EXO-AMYLASE
Overview
The three-dimensional structures of the catalytic residue Glu219-->Gln, mutant of Pseudomonas stutzeri maltotetraose-forming exo-alpha-amylase, and its complex with carbohydrate obtained by cocrystallization with, maltopentaose were determined. Two crystal forms were obtained for the, complexed enzyme, and a bound maltotetraose was found in each. The, structures were analyzed at 2.2 A and 1.9 A resolution, respectively for, the uncomplexed and complexed mutant. These structures were compared with, the wild-type enzyme structure. In the complexed crystals, the, maltotetraose was firmly bound, extensively interacting with the amino, acid environments in the active cleft. The non-reducing end glucose unit, was hydrogen bonded to the side-chain of Asp160 and the main-chain, nitrogen of Gly158, which seem to be predominantly required for the, recognition of the non-reducing end of the substrate that determines the, exo-wise degradation of this enzyme. The reducing end glucose unit of, bound maltotetraose showed clear deformation, adopting a half-chair, conformation with extensive hydrogen bonds to surrounding polypeptides., The C1-atom of this deformed glucose unit lies very close to Asp193OD1, with a distance of 2.6 A. The catalytic residue Asp294 is firmly, hydrogen-bonded to the O2 and O3-hydroxyl groups of the deformed reducing, end glucose unit. Upon binding of the carbohydrate, small but significant, induced fits were observed in the regions of Asp294, Phe156, Ile157, and, Asp160. Possible roles of the three catalytic residues are also discussed.
About this Structure
1JDA is a Single protein structure of sequence from Pseudomonas stutzeri with CA as ligand. Active as Glucan 1,4-alpha-maltotetraohydrolase, with EC number 3.2.1.60 Full crystallographic information is available from OCA.
Reference
Crystal structures of a mutant maltotetraose-forming exo-amylase cocrystallized with maltopentaose., Yoshioka Y, Hasegawa K, Matsuura Y, Katsube Y, Kubota M, J Mol Biol. 1997 Aug 29;271(4):619-28. PMID:9281429
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