Various esterases, lipases, and proteases with esterolytic activity were investigated for their power to catalyse deacetylation of 1,6-anhydro-2,3,4-tri-O-acetyl-β-D-glucopyranose. Out of these, chymotrypsin, esterase ex liver, lipase ex pancreas, and lipase ex wheat-germ have been found to be selective catalysts of deacetylation; chymotrypsin and wheat-germ lipase preferably removed the acetyl at C(3), whereas liver esterase and pancreas lipase the acetyl at C(4). Compared to chemical catalysis, whether by methanolic hydrogen chloride or hydrazine hydrate, the locoselectivity of the enzyme-catalysed deacetylation appear to be much better.
Lipase ex pancreas (EC 3.1.1.3), lipase ex wheat-germ (EC 3.1.1.3), and chymotrypsin (EC 3.4.4.5) are compared in their power to catalyse deacylation of 1,6-anhydro-2,3,4-tri-O-butyryl-β-D-glucopyranose. The action of the three enzymes has been found locoselective. In the use of a hydrolase the selectivity of the reaction was affected by composition of the reaction mixture. Lipase ex porcine pancreas in a solution containing 20% of methanol (v/v) catalysed deacylation preferentially from C-2, but on raising the methanol concentration to 50% (v/v) deacylation from C-4 prevailed over that from C-2. Analogously, at the lower methanol concentration deacylation effected by wheat-germ lipase occurred to a greater extent on C-2, whereas at the higher concentration on C-3. With chymotrypsin ex hog pancreas at the lower concentration of methanol the prevailing deacylation was on C-4, at the higher on C-3. Compared to a chemically catalysed hydrolysis, whether by methanolic hydrogen chloride or hydrazine hydrate, the locoselectivity of an enzyme-catalysed deacylation of 1,6-anhydro-2,3,4-tri-O-butyryl-β-D-glucopyranose is substantially higher.
Separation of tetroses has been achieved by gas chromatography of their per-O-MesSi oximes on a capillary column coated with OV-17. Trioses could be satisfactorily separated on a packed column with SP-2340 as a stationary phase. The achieved resolution R ^1 fulfills criteria required for quantitative analysis. Mass spectra of the title derivatives are also presented.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.