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

Flavonoids (103 species) were tested for inhibitory activity against mouse liver sialidase using sodium p-nitrophenyl-N-acetyl-alpha-D-neuraminate (PNP-NeuAc) as substrate. Isoscutellarein-8-O-glucuronide from the leaf of Scutellaria baicalensis showed most potent activity (IC50, 40 microM), and this flavone appeared to be a non-competitive inhibitor of the enzyme. This flavone inhibited the lysosomal solubilized sialidase against PNP-NeuAc and sialyllactose effectively, but not microsomal enzyme against gangliosides and colominic acid, whereas, negligible or weak inhibitory activities were observed for influenza virus sialidase, beta-galactosidase, alpha-mannosidase, and alpha-glucosidase tested. These results indicate that this flavone may be useful to elucidate the function of the lysosomal solubilized sialidase.
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PMID:Inhibition of mouse liver sialidase by plant flavonoids. 277 64

A novel substrate, beta-2-chloro-4-nitrophenylmaltopentaoside (beta CNPG5), was used for the enzyme-coupled determination of alpha-amylase in biological fluids. It was hydrolyzed specifically by alpha-amylase to about 90% producing beta-2-chloro-4-nitrophenylmaltoside (beta CNPG2) and maltotriose. Under the assay conditions, the absorption of 2-chloro-4-nitrophenol (CNP) generated by the secondary reaction of alpha-glucosidase and beta-glucosidase as auxiliary enzymes is about twice the absorption of 4-nitrophenol (PNP), which is the end product currently measured in some alpha-amylase assay methods. The sensitivity of the assay using beta CNPG5 was thus much higher than that using 4-nitrophenyl-maltopentaoside (PNPG5) as substrate. The absorption of CNP did not fluctuate with temperature or with pH between 6.8 and 7.2, which are the conditions normally used for determination of amylase activity in biological fluids.
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PMID:Determination of alpha-amylase in biological fluids using a new substrate (beta-2-chloro-4-nitrophenyl-maltopentaoside). 387 77

Replacement of the catalytic nucleophile Asp481 by glycine in Schizosaccharomyces pombe alpha-glucosidase eliminated the hydrolytic activity. The mutant enzyme (D481G) was found to catalyze the formation of an alpha-glucosidic linkage from beta-glucosyl fluoride and 4-nitrophenyl (PNP) alpha-glucoside to produce two kinds of PNP alpha-diglucosides, alpha-isomaltoside and alpha-maltoside. The two products were not hydrolyzed by D481G, giving 41 and 29% yields of PNP alpha-isomaltoside and alpha-maltoside, respectively. PNP monoglycosides, such as alpha-xyloside, alpha-mannoside, or beta-glucoside, acted as the substrate, but PNP alpha-galactoside and maltose could not. No detectable product was observed in the combination of alpha-glucosyl fluoride and PNP alpha-glucoside. This study is the first report on an "alpha-glycosynthase"-type reaction to form an alpha-glycosidic linkage.
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PMID:Alpha-glucosidase mutant catalyzes "alpha-glycosynthase"-type reaction. 1203 80

BACKGROUND: The permanently impaired protein folding during recombinant protein production resembles the stress encountered at extreme temperatures, under which condition the putative holding chaperones, IbpA/IbpB, play an important role. We evaluated the impact of ibpAB deletion or overexpression on stress responses and the inclusion body metabolism during production of yeast alpha-glucosidase in Escherichia coli. RESULTS: Deletion of ibpAB, which is innocuous under physiological conditions, impaired culture growth during alpha-glucosidase production. At higher temperatures, accumulation of stress proteins including disaggregation chaperones (DnaK and ClpB) and components of the RNA degradosome, enolase and PNP, was intensified. Overexpression of ibpAB, conversely, suppressed the heat-shock response under these conditions. Inclusion bodies of alpha-glucosidase started to disaggregate after arrest of protein synthesis in a ClpB and DnaK dependent manner, followed by degradation or reactivation. IbpA/IbpB decelerated disaggregation and degradation at higher temperatures, but did hardly influence the disaggregation kinetics at 15 degrees C. Overexpression of ibpAB concomitant to production at 42 degrees C increased the yield of alpha-glucosidase activity during reactivation. CONCLUSIONS: IbpA/IbpB attenuate the accumulation of stress proteins, and - at high temperatures - save disaggregated proteins from degradation, at the cost, however, of delayed removal of aggregates. Without ibpAB, inclusion body removal is faster, but cells encounter more intense stress and growth impairment. IbpA/IbpB thus exert a major function in cell protection during stressful situations.
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PMID:The small heat-shock proteins IbpA and IbpB reduce the stress load of recombinant Escherichia coli and delay degradation of inclusion bodies. 1570 88