Amylomaltase of Pyrobaculum aerophilum IM2 produces thermoreversible starch gels
article
Amylomaltases are 4-α-glucanotransferases (EC 2.4.1.25) of glycoside hydrolase family 77 that transfer α-1,4-linked glucans to another acceptor, which can be the 4-OH group of an α-1,4-linked glucan or glucose. The amylomaltase-encoding gene (PAE1209) from the hyperthermophilic archaeon Pyrobaculum aerophilum IM2 was cloned and expressed in Escherichia coli, and the gene product (PyAMase) was characterized. PyAMase displays optimal activity at pH 6.7 and 95°C and is the most thermostable amylomaltase described to date. The thermostability of PyAMase was reduced in the presence of 2 mM dithiothreitol, which agreed with the identification of two possible cysteine disulfide bridges in a three-dimensional model of PyAMase. The kinetics for the disproportionation of malto-oligosaccharides, inhibition by acarbose, and binding mode of the substrates in the active site were determined. Acting on gelatinized food-grade potato starch, PyAMase produced a thermoreversible starch product with gelatin-like properties. This thermoreversible gel has potential applications in the food industry. This is the first report on an archaeal amylomaltase. Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Topics
Food technologyEscherichia coliGelsGlucoseMathematical modelspH effectsStarchAchaeal amylomaltaseAmylomaltaseBinding modePyrobaculum aerophilum IM2Enzyme kinetics4alpha glucanotransferaseAcarboseCysteineDisulfideDithiothreitolGelatinGene productGlucanGlucoseGlycosidaseHydroxyl groupOligosaccharidePotato starchStarchEnzymeArcheanChemical reaction kineticsEnzyme active siteEnzyme activityEnzyme inhibitionEnzyme substrate complexEscherichia coliFood industryGene expressionHeat sensitivityMolecular cloningNonhumanPyrobaculumPyrobaculum aerophilumThermostabilityBinding SitesCloning, MolecularEnzyme StabilityEscherichia coliFood IndustryGelsGlycogen Debranching Enzyme SystemHeatKineticsPyrobaculumStarchArchaeaEscherichia coliPyrobaculum aerophilumSolanum tuberosum
TNO Identifier
238663
ISSN
00992240
Source
Applied and Environmental Microbiology, 71(9), pp. 5098-5106.
Pages
5098-5106