Reverse Reaction of Aspergillus niger APC-9319 [alpha]-Galactosidase in a Supersaturated Substrate Solution

• Published in: Bioscience, biotechnology, and biochemistry Vol. 69; no. 7; p. 1381
• Main Authors: YAMASHITA, Akiko, HASHIMOTO, Hiroyuki, FUJITA, Koki, OKADA, Masamichi, MORI, Shigeharu, KITAHATA, Sumio
• Format: Journal Article
• Language: English
• Published: Tokyo Oxford University Press 01.07.2005
• ISSN: 0916-8451; 1347-6947

The α-galactosidase that effectively catalyzes a reverse reaction of galactose, Aspergillus niger APC-9319 α-galactosidase, was screened from industrial enzyme preparations for food processing containing α-galactosidase activity. Reverse reaction of A. niger APC-9319 α-galactosidase was performed using a supersaturated solution (90% galactose [w/v]). A. niger APC-9319 α-galactosidase was not inhibited even in high substrate concentration, and effectively catalyzed the reverse reaction. The yield of the reaction product, α-linked galactooligosaccharide (α-GOS), increased greatly as the initial concentration of galactose increased to 90% (w/v), and was more than 50%. Furthermore, the half life of enzyme activity was about three times as long as that using 60% galactose (w/v). α-GOS (1.4 g) was prepared from galactose (3.0 g) by reverse reaction of A. niger APC-9319 α-galactosidase. The α-GOS contained 58% α-galactobiose (α-Gal2), 28% α-galactotriose, and 14% oligosaccharides larger than α-galactotriose. The main component of positional isomers in α-Gal2 was α-1,6Gal2.