Potential Applications of Plant Glycohydrolases for Oligosaccharide Synthesis

Abstract

Reversal of hydrolytic enzymes is an alternative approach for oligosaccharide synthesis. Thus, we have screened for the hydrolytic activity of nine glycohydrolase enzymes from the seeds of some fifty Thai plant species from 17 families, with a view to selecting suitable enzymes to reverse. Good sources of α-D-mannosidase, β-D-glucosidase, β-D-fucosidase, and β-D-galactosidase were found. Some have been purified including a β-D-glucosidase/β-D-fucosidase enzyme from Thai Rosewood (Dalbergia cochinchinensis Pierre) and a β-D-galactosidase from Thai Jute (Hibiscus sabdariffa L.var altissima),and their kinetic and other properties have been investigated. Synthesis of oligosaccharides by reversal of hydrolytic enzymes was studied by incubation with high concentrations of monosaccharide substrates for 1–20 days at elevated temperature, followed by analysis of products by h.p.l.c. Typically, disaccharide and trisaccharide products could be readily detected confirming synthetic capability. In general, total synthesis at equilibrium was higher (about 35–75%) for α-D-mannosidase than for β-D-glucosidase (15–25%) or for β-D-galactosidase (10–15%).

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