Thesis (Ph. D.)--Lehigh University, 2001. / Includes vita. Includes bibliographical references (leaves 58-68).

In this study, alpha-Galactosidase (alpha-D-galactoside-galactohydrolase, EC 3.2.1.22) has been isolated, purified, and characterized from intracellular fraction of Lactobacillus helveticus ATCC 10797. It was purified by a combination of ammonium sulfate precipitation and fast performance liquid chromatography system using ion exchange and gel-filtration columns. This enzyme was purified to only 9.44 fold over the crude extract with a recovery of 1.8%. The km of 3.83 mM and Vmax of 416.44 mumol/min/mg protein were calculated from PNPG. The molecular mass was estimated to be 188 kDa by gel-filtration, but 90 kDa by SDS-PAGE, indicating two similar molecular weight subunits. The optimum temperature for enzyme activity was 37°C, but with a stability below 30°C. The optimum pH was at 6 with a stability of pH 4-8 range. / This enzyme was activated by 10 mM monovalent ions such as K+ , NH4+, Li+ and CS +, while the activity was inhibited by divalent ions such as Cu +2, Zn+2, F+2. About 40% of the enzyme activity was inhibited with 100 mM EDTA. alpha-Galactosidase was inhibited by 1mM glucose and galactose, 10 mM sucrose, high concentrations of melibiose, or raffinose and stachyose, but the least inhibitory effect was shown with fructose. / When the sugars were incubated with alpha-galactosidase, melibiose was hydrolyzed to glucose and galactose, raffinose to galactose and sucrose, while stachyose to galactose and sucrose with raffinose as intermediate product.

Th.--Sci. phys.--Lille 1, 1977. N°: 398.

Th. 3e cycle--Chim. moléculaire--Grenoble--I.N.P.E., 1979. N°: 117.

The first conduritol aziridine (1,2-dideoxy-1,2-epimino-myo-inositol, 1) was synthesized in seven steps from myo-inositol (2) and inhibits pABG5 β-glucosidase and yeast ⍺-glucosidase irreversibly. 1,2-0-Cyclohexylidene-myo-inositol (3) was obtained by reaction of 2 with cyclohexanone. Benzylation of 3 followed by hydrolysis of the ketal gave l,4,5,6-tetra-0-benzyl-myo-inositol (5). The two free hydroxyl groups in 5 were methanesulfonylated and the axial mesyl group in l,4,5,6-tetra-0-benzyl-2,3-di-0-methanesulfonyl-myo-inositol (12) was selectively displaced by an azido group. The resulting 1-azido-2,3,4,5-tetxa-0-benzyl-1-deoxy-6-0-methanesulfonyl-scyllo-inositol (13) was hydrogenated in the presence of HC1 to give 1-amino-1-deoxy-2-0-methanesulfonyl-scyllo-inositol (24) hydrochloride. Cyclisation of 24 under basic aqueous conditions yielded DL-1. [Formula Omitted] The dissociation constant Ki and the inactivation rate constant ki for inactivation of pABG5 β-glucosidase by 1 were calculated to be 3.0 mM and 0.077 min⁻¹ respectively. For yeast ⍺-glucosidase inactivation, values of Ki, and ki were found to be 9.5 mM and 0.39 min-1 respectively. Finally, 24 and 31 were tested as reversible (non-covalent) inhibitors of both the glucosidases and the respective inhibition constants (Ki) determined. / Science, Faculty of / Chemistry, Department of / Graduate

No description available.

Thesis (Ph.D.)--University of Western Australia, 2007.

No description available.

No description available.

Reproduction de : Thèse de doctorat : Biochimie et biologie moléculaire : Reims : 2005. / Résumé en français et en anglais. Titre provenant de l'écran titre. Bibliogr. f. 199-218.