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Abstract
Bacillus circulans WL-12 1,3-β-d-glucanases are extracellular enzymes subject to catabolite repression by glucose and synthesized after the depletion of this sugar. Utilization of other complex carbon sources (1,3-β-d-glucan from baker’s yeast, laminarin or xylan) resulted in a 3-to 4-fold increase in the formation of these enzymes, suggesting that they are derepressible and inducible. Under induction conditions four different enzymes were detected by isoelectric focusing that were numbered I, II, III and IV, according to their isoelectric points (3·7, 4·6, 5·5 and 6·5 respectively). Glucanase II was inducible whereas I, III and IV were both derepressible and inducible. In addition, the synthesis of glucanase II was blocked by cyclic AMP. The four enzyme forms displayed an endo- attack on laminarin and yielded similar products, but differed in some physico-chemical parameters such as molecular weight, K m and lytic activity.
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