Title: Comparison of<i>o</i>-Phthalaldehyde Modification of<i>α</i>-Amylase from Porcine Pancreas and<i>Bacillus subtilis</i>with Taka-amylase A
Abstract: A fluorescent reagent, o-phthalaldehyde (OPA), competitively inhibited porcine pancreatic α-amylase (PPA) with Ki values of 0.7–0.9 mM, while α-amylase from Bacillus subtilis (BS) was uncompetitively inhibited, with Ki values of 5.8–7.6 mM. In both cases, OPA gave a time-dependent irreversible inactivation, where the amylase activity was lost faster than the maltosidase activity. Zymograms of the course of OPA modification showed that PP A was converted into at least six, faster moving components and BS gave two components. The OPA modification was retarded by the addition of the substrate analog, cyclodextrins, and the OPA modified enzymes decreased in affinity for the substrate soluble starch. Stoichiometric measurement showed that both PPA and BS was inactivated by the incorporation of 1 mol of OPA per mol of enzyme. The role of OPA modification of α-amylases was discussed in relation to the regulation of catalytic activity of enzymes.
Publication Year: 1995
Publication Date: 1995-01-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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