Studies on the .BETA.-1,3-glucanase system of streptomyces. Part II. A preparation method of gentiobiose from curdlan using the enzyme system from Streptomyces sp.

Abstract

A new enzyme system which produces gentiobiose from curdlan (β1, 3-glucan) was discovered in the culture filtrate of Streptomyces, and a preparation method for gentiobiose using the enzyme system was investigated. The optimum pH and temperature of the enzyme system for curdlan-decomposing activity were 5.0 and 55°C, respectively.The enzyme system was stable at pH 3.0 to 7.0 on 1 hr incubation at 37°C.The treatment at 60°C for 3hr showed a complete loss of the activity. On the other hand, a suitable pH for gentiobiose formation from curdlan was 6.0.When curdlan was hydrolyzed by the enzyme system under optimum conditions for the formation of gentiobiose (pH 6.0 and 50°C), the resultant hydrolyzate was composed mainly of glucose and gentiobiose in an approximate ratio of 4:1 by weight.Moreover, the yield of gentiobiose based on curdlan increased when the enzyme reaction was initiated with the addition of glucose to the reaction mixture.By the application of the enzyme system, the hydrolyzate containing 18.5 g of gentiobiose was obtained from 50 g (42.3 g as anhydroglucose) of curdlan and 100 g of glucose, and 14.7 g of crystalline gentiobiose was obtained after separation by carbon column chromatography.