Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previously, we constructed a gene disruption in the pullulanase I gene of Bacteroides thetaiotaomicron 5482A. This mutant, designated B. thetaiotaomicron 95-1, had a lower level of pullulanase specific activity than did wild-type B. thetaiotaomicron but still exhibited a substantial amount of pullulanase activity. Characterization of the remaining pullulanase activity present in B. thetaiotaomicron 95-1 has identified an alpha(1----4)-D-glucosidic bond cleaving pullulanase which has been tentatively designated a neopullulanase. The neopullulanase (pullulanase II) is a 70-kDa soluble protein which cleaves alpha(1----4)-D-glucosidic bonds in pullulan to produce panose. The neopullulanase also cleaved alpha(1----4) bonds in amylose and in oligosaccharides of maltotriose through maltoheptaose in chain length. An alpha-glucosidase from B. thetaiotaomicron 95-1 was characterized. The alpha-glucosidase was partially purified to a preparation containing three proteins of 80, 57, and 50 kDa. Pullulan and amylose were not hydrolyzed by the alpha-glucosidase. alpha(1----4)-D-Glucosidic oligosaccharides from maltose to maltoheptaose were hydrolyzed to glucose by the alpha-glucosidase. The alpha-glucosidase also hydrolyzed alpha(1----6)-linked oligosaccharides such as panose (the product of the pullulanase II action on pullulan) and isomaltotriose.
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PMID:Characterization of a neopullulanase and an alpha-glucosidase from Bacteroides thetaiotaomicron 95-1. 170 85

1. Pullulanase synthesis was studied in 16 classified (N.C.I.B.) strains and in an industrial strain (R) of Klebsiella aerogenes grown in chemostats containing maltose as inducer and sole carbon source. 2. Maximum synthesis was associated with carbon-limited growth at a low dilution rate (about 0.2h(-1)). The enzyme remained firmly cell-bound and seemed to be located on the cell surface. 3. Three strains had high activity (R, N.C.I.B. 5938, 8017), twelve were intermediate, and two (N.C.I.B. 8153, 9146) had negligible activity but were inducible with pullulan. 4. Pullulan similarly induced low, but adequate, activity in the other strains in conditions (nutrient limitation other than carbon-limitation) in which pullulanase was otherwise very seriously repressed. Nevertheless, in carbon limitation pullulan induced no more enzyme than did maltose, maltotriose or oligosaccharide mixtures, and ;hyperactivity' never developed on protracted culture. 5. Cyclic AMP relieved the transient repression produced by adding glucose to maltose-limited cultures and a further change to glucose-limited conditions led to constitutive pullulanase synthesis. 6. Amylomaltase and alpha-glucosidase activities were also examined but in less detail. 7. The presence of pullulanase in maltose-limited growth is discussed, but no clear function can be assigned to it at present. The molar growth yields for all the strains were very similar, and no correlation was found between the overgrowth of one strain by another and pullulanase activity. Further, any function as a general branching enzyme in polysaccharide synthesis seems unlikely.
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PMID:Pullulanase synthesis in klebsiella (aerobacter) aerogenes strains growing in continuous culture. 437 62