Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.2.1.20 (alpha-glucosidase)
4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During meiosis in Saccharomyces cerevisiae, the polysaccharide glycogen is first synthesized and then degraded during the period of spore maturation. We have detected, in sporulating yeast strains, an enzyme activity which is responsible for the glycogen catabolism. The activity was absent in vegetative cells, appeared coincidently with the beginning of glycogenolysis and the appearance of mature ascospores, and increased progressively until spourlation was complete. The specific activity of glycogenolytic enzymes in the intact ascus was about threefold higher than in isolated spores. The glycogenolysis was not due to combinations of phosphorylase plus phosphatase or amylase plus maltase. Nonsporulating cells exhibited litle or no glycogen catabolism and contained only traces of glycogenolytic enzyme, suggesting that the activity is sporulation specific. The partially purified enzyme preparation degraded amylose and glycogen, releasing glucose as the only low-molecular-weight product. Maltotriose was rapidly hydrolyzed; maltose was less susceptible. Alpha-methyl-D-glucoside, isomaltose, and linear alpha-1,6-linked dextran were not attacked. However, the enzyme hydrolyzed alpha-1,6-glucosyl-Schardinger dextrin and increased the beta-amylolysis of beta-amylase-limit dextrin. Thus, the preparation contains alpha-1,4- and alpha-1,6-glucosidase activities. Sephadex G-150 chromatography partially resolved the enzyme into two activities, one of which may be a glucamylase and the other a debranching enzyme.
...
PMID:Glycogenolytic enzymes in sporulating yeast. 35 Aug 52

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.
...
PMID:Characterization of a neopullulanase and an alpha-glucosidase from Bacteroides thetaiotaomicron 95-1. 170 85

Extracts of germinated barley (Hordeum vulgare L.) seeds of 41 different genotypes were analyzed for their activities of alpha-amylase, beta-amylase, alpha-glucosidase, and debranching enzyme and for their abilities to hydrolyze boiled soluble starch, nonboiled soluble starch, and starch granules extracted from barley seeds with water. Linear correlation analysis, used to quantitate the interactions between the seven parameters, revealed that boiled soluble starch was not a good substrate for predicting activities of enzymes functioning in in vivo starch hydrolysis as the extracts' abilities to hydrolyze boiled soluble starch was not correlated with their abilities to hydrolyze native starch granules. Activities of alpha-amylase and alpha-glucosidase were positively and significantly correlated with the seed extracts' abilities to hydrolyze all three starches. beta-Amylase was only significantly correlated with hydrolysis of boiled soluble starch. No significant correlations existed between debranching enzyme activity and hydrolysis of any of the three starches. Interactions between the four enzymes as they functioned together to hydrolyze the three types of starch were evaluated by path coefficient analysis. alpha-Amylase contributed to hydrolyses of all three starches primarily by its direct effect (noninteractive component). This direct contribution increased as the substrate progressed from the completely artificial boiled soluble starch, to the most physiologically significant substrate, native starch granules. alpha-Glucosidase contributed to the hydrolysis of boiled soluble starch primarily by its direct effect (noninteractive) yet contributed to starch granule hydrolysis primarily via its interaction with alpha-amylase (indirect effect). The contribution of beta-amylase to hydrolysis of boiled soluble starch was direct and it did not contribute significantly to hydrolysis of native starch granules.
...
PMID:A quantitative assessment of the importance of barley seed alpha-amylase, beta-amylase, debranching enzyme, and alpha-glucosidase in starch degradation. 182 15

Bacteroides thetaiotaomicron can utilize amylose, amylopectin, and pullulan as sole sources of carbon and energy. The enzymes that degrade these polysaccharides were found to be primarily cell associated rather than extracellular. Although some activity was detected in extracellular fluid, this appeared to be the result of cell lysis. The cell-associated amylase, amylopectinase, and pullulanase activities partitioned similarly to the periplasmic marker, acid phosphatase, when cells were exposed to a cold-shock treatment. Two other enzymes associated with starch breakdown, alpha-glucosidase and maltase, appeared to be located in the cytoplasm. Intact cells of B. thetaiotaomicron were found to bind 14C-starch. Binding was probably mediated by a protein because it was saturable and was decreased by treatment of cells with proteinase K. Results of competition experiments showed that the starch-binding proteins had a preference for maltodextrins larger than maltohexaose and a low affinity for maltose and maltotriose. Both the degradative enzymes and starch binding were induced by maltose. These findings indicate that starch utilization by B. thetaiotaomicron apparently does not involve secretion of extracellular enzymes. Rather, binding of the starch molecule to the cell surface appears to be a first step to passing the molecule through the outer membrane and into the periplasmic space.
...
PMID:Biochemical evidence that starch breakdown by Bacteroides thetaiotaomicron involves outer membrane starch-binding sites and periplasmic starch-degrading enzymes. 272 47

Clostridium thermosulfurogenes displayed faster growth on either glucose, maltose, or starch than Clostridium thermohydrosulfuricum. Both species grew faster on glucose than on starch or maltose. The fermentation end product ratios were altered based on higher ethanol and lactate yields on starch than on glucose. In C. thermohydrosulfuricum, glucoamylase, pullulanase, and maltase were mainly responsible for conversion of starch and maltose into glucose, which was accumulated by a putative glucose permease. In C. thermosulfurogenes, beta-amylase was primarily responsible for degradation of starch to maltose, which was accumulated by a putative maltose permease and then hydrolyzed by glucoamylase. Regardless of the growth substrate, the rates of glucose, maltose, and starch transformation were higher in C. thermosulfurogenes than in C. thermohydrosulfuricum. Both species had a functional Embden-Meyerhof glycolytic pathway and displayed the following catabolic activities: ferredoxin-linked pyruvate dehydrogenase, acetate kinase, NAD(P)-ethanol dehydrogenase, NAD(P)-ferredoxin oxidoreductase, hydrogenase, and fructose-1,6-diphosphate-activated lactate dehydrogenase. Ferredoxin-NAD reductase activity was higher in C. thermohydrosulfuricum than NADH-ferredoxin oxidase activity, but the former activity was not detectable in C. thermosulfurogenes. Both NAD- and NADP-linked ethanol dehydrogenases were unidirectional in C. thermosulfurogenes but reversible in C. thermohydrosulfuricum. The ratio of hydrogen-producing hydrogenase to hydrogen-consuming hydrogenase was higher in C. thermosulfurogenes. Two biochemical models are proposed to explain the differential saccharide metabolism on the basis of species enzyme differences in relation to specific growth substrates.
...
PMID:Differential amylosaccharide metabolism of Clostridium thermosulfurogenes and Clostridium thermohydrosulfuricum. 393 39

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.
...
PMID:Pullulanase synthesis in klebsiella (aerobacter) aerogenes strains growing in continuous culture. 437 62

Ruminobacter amylophilus is an obligate anaerobe that uses only alpha-linked glucose molecules (i.e., maltose, maltodextrins, and starch) as a source of energy, making it an excellent model for the study of bacterial starch degradation. Constitutive amylase, amylopectinase, and pullulanase activities were found in intracellular and extracellular fractions of R. amylophilus. However, extracellular activities apparently resulted from cell lysis. Both soluble and membrane-bound polysaccharidase activities were detected. Most of the soluble polysaccharidase activity partitioned with the periplasmic cell fraction. No alpha-glucosidase or maltase activity was detected in either the cellular or extracellular fraction. In addition, intact cells of R. amylophilus bound U-14C-starch. This binding could be saturated and was constitutive and sensitive to proteinase K, indicating protein or protein complex mediation. Competition experiments showed that these starch-binding sites had equally high affinities for starch and maltodextrins larger than maltotriose. The sites had a reduced affinity for maltose and virtually no affinities for glucose and nonstarch polysaccharides. These findings suggest that R. amylophilus binds starch molecules to the cell surface as an initial step in transporting the molecule through the outer membrane and into the periplasmic space. Extracellular polysaccharides do not appear to be involved in starch degradation.
...
PMID:Biochemical analysis of starch degradation by Ruminobacter amylophilus 70. 753 78

Bacteroides thetaiotaomicron, a gram-negative colonic anaerobe, can utilize three forms of starch: amylose, amylopectin, and pullulan. Previously, a neopullulanase, a pullulanase, and an alpha-glucosidase from B. thetaiotaomicron had been purified and characterized biochemically. The neopullulanase and alpha-glucosidase appeared to be the main enzymes involved in the breakdown of starch, because they were responsible for most of the starch-degrading activity detected in B. thetaiotaomicron cell extracts. To determine the importance of these enzymes in the starch utilization pathway, we cloned the genes encoding the neopullulanase and alpha-glucosidase. The gene encoding the neopullulanase (susA) was located upstream of the gene encoding the alpha-glucosidase (susB). Both genes were closely linked to another starch utilization gene, susC, which encodes a 115-kDa outer membrane protein that is essential for growth on starch. The gene encoding the pullulanase, pulI, was not located in this region in the chromosome. Disruption of the neopullulanase gene, susA, reduced the rate of growth on starch by about 30%. Elimination of susA in this strain allowed us to detect a low residual level of enzyme activity, which was localized to the membrane fraction. Previously, we had shown that a disruption in the pulI gene did not affect the rate of growth on pullulan. We have now shown that a double mutant, with a disruption in susA and in the pullulanase gene, pulI, was also able to grow on pullulan. Thus, there is at least one other starch-degrading enzyme besides the neopullulanase and the pullulanase. Disruption of the alpha-glucosidase gene, susB, reduced the rate of growth on starch only slightly. No residual alpha-glucosidase activity was detectable in extracts from this strain. Since this strain could still grow on maltose, maltotriose, and starch, there must be at least one other enzyme capable of degrading the small oligomers produced by the starch-degrading enzymes. Our results show that the starch utilization system of B. thetaiotaomicron is quite complex and contains a number of apparently redundant degradative enzymes.
...
PMID:Contribution of a neopullulanase, a pullulanase, and an alpha-glucosidase to growth of Bacteroides thetaiotaomicron on starch. 895 99

Starch supported growth of continuous cultures of Bacteroides ovatus when this carbohydrate provided the sole source of carbon and energy. Inducible amylase and alpha-glucosidase activities were inversely related to dilution rate in starch-limited and starch-excess chemostats over the dilution rate (D) range D = 0.03/h to D =0.20/h, and were partly repressed during growth under conditions of starch-excess. Preparative isoelectric focusing of B. ovatus cytoplasmic extracts indicated the existence of three distinct starch-hydrolyzing enzymes. Incubation of active fractions from the isoelectric focusing cell with maltose and a variety of low-molecular-weight oligosaccharides (maltotriose, maltotetraose, maltopentaose, maltohexaose, maltoheptaose) identified a single amylase activity, an enzyme with combined beta-amylase and glucoamylase/alpha-glucosidase properties, and also a possible pullulanase. The ability of B. ovatus to synthesize several starch-hydrolyzing enzymes with different specificities and activities may confer a significant competitive advantage to this organism in the colonic ecosystem.
...
PMID:Starch utilization by Bacteroides ovatus isolated from the human large intestine. 909 29

In addition to the previously identified 4-alpha-glucanotransferase gene mgtA and the alpha-amylase gene amyA of Thermotoga maritima strain MSB8 we have now isolated three further genes encoding amylolytic enzymes from a gene library of this ancestral bacterium. The genes code for the extremely thermostable enzymes pullulanase (pulA), maltodextrin phosphorylase (agpA) and alpha-glucosidase (aglA) and have the potential to encode polypeptides with calculated molecular masses of 96.3 kDa, 96.1 kDa and 52.5 kDa, respectively. Comparative amino acid sequence analysis revealed that PulA and AgpA are clearly related to other known enzymes with similar function. AglA, on the other hand, was not related to other alpha-glucosidases but appears to belong to an enzyme family containing alpha-galactosidases and 6-phospho-beta-glucosidases. Enzyme properties are reported which demonstrate the extreme thermostability of these T. maritima enzymes.
...
PMID:Isolation and analysis of genes for amylolytic enzymes of the hyperthermophilic bacterium Thermotoga maritima. 945 51


1 2 3 Next >>

---