Enzymatic properties of α- d-galactosidase from Trichoderma reesei

• Published in: Carbohydrate research Vol. 296; no. 1; pp. 261 - 273
• Main Authors: Savel'ev, Andrew N., Ibatyllin, Farid M., Eneyskaya, Elena V., Kachurin, Anatoly M., Neustroev, Kirill N.
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 24.12.1996; Elsevier
• Subjects: Biochemistry & Molecular Biology; Chemistry; Chemistry, Applied; Chemistry, Organic; Galactopyranosylamines; Hypocrea jecorina; Kinetic scheme; Life Sciences & Biomedicine; Physical Sciences; Science & Technology; Transglycosylation; Trichoderma reesei; α- d-Galactosidase; Transglycosylation; Kinetic scheme; Trichoderma reesei; Galactopyranosylamines; α- d-Galactosidase; alpha-D-galactosidase; galactopyranosylamines; kinetic scheme; transglycosylation; PURIFICATION
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/S0008-6215(96)00248-0

The kinetics of hydrolysis of a number of natural and synthetic substrates [melibiose, raffinose, stachyose, methyl α- d-galactopyranoside, and p-nitrophenyl α- d-galactopyranoside (PNPG)], catalyzed by α- d-galactosidase from the fungus Trichoderma reesei, has been studied. A number of N-acyl-α-d-galactopyranosylamines, which are competitive inhibitors of α- d-galactosidase, have been synthesized, and the K I values for these compounds have been obtained. The inhibiting properties of the competitive inhibitors of d-galactose, 1,5-anhydro- d-galactitol, and 2-deoxygalactose have been compared, and reasons for differences in K I values between these compounds have been discussed. It has been shown that α- d-galactosidase exhibits transglycosylating activity; the main product of transglycosylation in the reaction with PNPG is p-nitrophenyl 6- O- α-d-galactopyranosyl-α-d-galactopyranoside. The hydrolysis inhibition in the presence of a substrate has been shown to correlate with the substrate transglycosylation. Data of steady-state kinetics together with data of presteady-state kinetics obtained by the stop-flow method suggest that an intermediate galactosyl-enzyme complex is formed in the reaction and is of particular importance in the processes under study. A minimal kinetic scheme describing the experimental data obtained is proposed.