Inactivation of alpha-amylases from Thermoactinomyces vulgaris R-47, TVA I and TVA II, by omega-epoxyalkyl alpha-D-glucopyranoside
2005
Uotsu, N.(Tokyo Univ. of Agriculture and Technology, Fuchu (Japan)) | Tonozuka, T. | Yokota, T. | Kobayashi, A. | Nishikawa, A. | Sakano, Y.
We found here that (1)-epoxyalkyl alpha-D-glucopyranosides consisting of three, four and five alkyl carbons (alpha-E3G, alpha-E4G and alpha-E5G, respectively), which are known to be affinity-labeling reagents of beta-amylasce, had the effect of inactivating two pullulan-hydrolyzing alpha-amylases from Thermoactinomyces vulgaris R47, TVA I and TVA II, at high concentration (ca . 0.1 ¨C 1.5 M). The inactivation exhibited saturation kinetics of a two-step mechanism, and an inactivation rate constant, k, and equilibrium dissociation constant K(R), of alpha-E5G were calculated. The k/K(R) values of alpha-E5G for TVA I and TVA II were 13.1 x 10(-4) and 6.41 x 10(-4) M(-1). S(-1) respectively. In terms of the power of inactivation, the orders for TVA I and TVA II were alpha£E5G£¾alpha£E3G near equal alpha-E4G, and alpha-E5Galpha-E3G alpha-E4G, respectively. The findings indicated that the relation between the lengths of the alkyl carbons and the inactivation of TVA I and TVA II differs from that for beta-amylase and isomalto-dextranase.
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