Suitably configured allyl ethers of unsaturated cyclitols act as substrates β-glycosidases, reacting via allylic cation transition states. Incorporation halogens at the vinylic position these carbasugars, along with an activated leaving group, generates potent inactivators β-glycosidases. Enzymatic turnover halogenated (F, Cl, Br) displayed a counter-intuitive trend wherein most electronegative...

The sensitive to freezing2-1 (sfr2-1) mutation causes freezing sensitivity in Arabidopsis thaliana. By mapping, transgenic complementation, and sequencing, sfr2-1 was revealed to be a mutation in gene At3g06510. A new knockout allele was obtained, and its identical freezing-sensitive phenotype confirmed that the SFR2 gene product is essential for freezing tolerance. Transcription of SFR2 was ob...

The sensitive to freezing2-1 (sfr2-1) mutation causes freezing sensitivity in Arabidopsis thaliana. By mapping, transgenic complementation, and sequencing, sfr2-1 was revealed to be a mutation in gene At3g06510. A new knockout allele was obtained, and its identical freezing-sensitive phenotype confirmed that the SFR2 gene product is essential for freezing tolerance. Transcription of SFR2 was ob...

The enzymes, cr-galactosidase, P-galactosidase, a-mannosidase, P-glucosidase, and p-acetylglucosaminidase, have been purified from the germinating seeds of Phaseolus vulgaris. All five enzymes have been simultaneously isolated in a highly active form. The pH optimum, K,,,, and energy of activation of each glycosidase for the reaction of hydrolysis of the appropriate P-nitrophenyl glycoside have...

Lactase-phlorizin hydrolase was isolated by immunoadsorption chromatography from rabbit brush-border membrane vesicles. Inactivation of the enzyme with [3H]conduritol-B-epoxide, a covalent active site-directed inhibitor, labeled glutamates at positions 1271 and 1747. Glu1271 was assigned to lactase, Glu1747 to phlorizin hydrolase activity. In contrast, the nucleophiles in the active sites of su...

The pH optima and apparent Km and Vmax values were determined for nine glycosidases of the retinal pigment epithelium (RPE) of the calf. In terms of micromoles of substrate cleaved per milligram protein per hour, the following relative order of enzymatic activities was observed: beta-N-acetylglucosaminidase greater than alpha-glucosidase = beta-N-acetylgalactosaminidase greater than alpha-manno...

The monosaccharide u&s most commonly found in glycoproteins are n-galactose, n-mannose, M-acetyl-u-glucosamine, sialic acid, and L-fucose. The hydrolysis of individual carbohydrate units by specific glycosidases is an excellent tool for studying the sequenbial arrangement and anomeric configuration of the carbohydrate units in the glycoproteins. In previous studies, cr-mannosidase (cr-u-mannosi...

Because the normal faecal flora includes bacteria which can produce mucus-digesting glycosidases, it follows that increased digestion of colonic mucus by these bacterial enzymes could be important in the pathogenesis of ulcerative colitis. Faecal activities of potential mucus-degrading glycosidases have therefore been assayed in samples from patients with inflammatory bowel disease and normal c...

Structural bioinformatics approaches applied to the alpha- and beta-glycosidases from the GH4 enzyme family reveal that, despite low sequence identity, these enzymes possess quite similar global structural characteristics reflecting a common reaction mechanism. Locally, there are a few distinctive structural characteristics of GH4 alpha- and beta-glycosidases, namely, surface cavities with diff...