Activity of Glucose Isomerase from Bacillus thuringiensis under Different Treatments

Abstract

Bacillus thuringiensis is a Gram-positive bacterium naturally found in soil, water and grain dust, and can be cultivated in liquid, solid and semi-solid media. Glucose isomerase (EC. 5.3.1.5) catalyzes the reversible isomerization of glucose to fructose and that of xylose to xylulose. It is an important enzyme used in the industrial production of high-fructose corn syrup (HFCS). Glucose isomerase was purified from Bacillus thuringiensis. The final purification resulted in a considerably high yield (64.6%) with about 15.8-fold. The optimum temperature and pH were 50 ◦C and 7.0. The optimum glucose concentration was 8 mM. Glucose isomerase required Mn2+ or Ca2+ as cofactor. The enzyme was activated by cysteine, ascorbic acid, folic acid and sodium sulfate. The enzyme was inhibited by sodium bromide, sodium azide, sodium fluoride, sodium arsenate, glycine, tyrosine, phenylalanine, arginine, asparagine, and guanidine hydrochloride. Pyruvate, glyoxylate and 2-oxoglutarate inhibited the enzyme activity at the higher concentrations.