Crystal structure of a maltotetraose-formingexo-amylase from Pseudomonas stutzeri 1 1Edited by R. Huber

Crystal structures of a mutant maltotetraose-forming exo-amylase cocrystallized with maltopentaose 1 1Edited by R. Huber

“…The overall architecture and main-chain conformations of the molecule are almost identical to those of the wild-type enzyme (Morishita et al, 1997) , except in the region where the maltotetraose is bound in the active site in the complexed crystals. The geometries of the two bound calcium ions are also the same.…”

“…About 100 bound water molecules were found at the same site within distances of 1 A Ê among the wild-type and two complexed crystals. Buried water molecules found in the wild-type crystal (Morishita et al, 1997) were almost conserved. The disordered loop composed of the residues 66 to 72 was more rigid in the complex type 1 crystal, but still showed disorder in the type 2 crystal (a little less than in the wild-type, but with high temperature factors).…”

“…These a-amylases were from sources of Aspergillus oryzae (Matsuura et al, 1984;Boel et al, 1990), Aspergillus niger (Boel et al, 1990), porcine pancreas (Larson et al, 1994), barley (Kadziola et al, 1994), Bacillus licheniformis (Machius et al, 1995), and human saliva (Ramasubbu et al, 1996). Structure analyses of exotype amylases have been done for non a-amylases, soybean b-amylase (Mikami et al, 1994), and glucoamylase (Aleshin et al, 1992), and recently for an a-amylase, Pseudomonas stutzeri maltotetraoseforming exo-amylase (G4-amylase; Morishita et al, 1997). The structures of cyclodextrin glycosyltransferases from Bacillus circulans (Klein & Schulz, 1991;Strokopytov et al, 1995) and Bacillus stearothermophilus (Kubota et al, 1991) have also been analyzed.…”

Biology of Pseudomonas stutzeri

“…The enzymology of the exo-amylase-which is responsible for the formation of maltotetraose as an end product-has been examined at the molecular level. This enzyme has also been cloned (231). Obradors and Aguilar demonstrated that polyethylene glycol was degraded to yield ethylene glycol, a substrate typically used by P. stutzeri strains (241).…”

Molecular Mechanism inα-Glucosidase and Glucoamylase

“…6 ) On the other hand, the X-ray crystallographic analyses have been made also for Bacillus eirculans 7) and B. srearothermoplzilus cyclodextrin glucanotransferases (CGTase),8,9) soybean fJ-amylase,10~12) A. awamori glucoamylase. 13 ) and B. cereus a-glucosidase 14 ) though this type of ex-glucosidase has no starch-hydrolyzing activity.…”