Quantitative determination of anomeric forms of sugar produced by amylases. V. Anomeric forms of maltose produced in the hydrolytic reaction of substituted phenyl alpha-maltosides catalyzed by saccharifying alpha-amylase from B. subtilis.

1. Hydrolyses of phenyl alpha-maltoside and its derivatives with various substituents (p-NO2, p-C1, p-CH3, p-C2H5, and p-C(CH3)3) catalyzed by saccharifying alpha-amylase from B. subtilis3 [EC 3.2.1.1] were studied under conditions such that the products were only maltose and the corresponding phenols (1), in order to determine quantitatively the anomeric form of the sugar produced from each substrate. 2. At the optimum pH of this enzyme (pH-5.4), maltose released from all the substituted substrates studied was entirely in the beta-form. These results are in remarkable contrast to the previous finding that alpha-maltose is exclusively produced from unsubstituted phenyl alpha-maltoside by this enzyme (2). 3. At pH 6.18 and 6.73, maltose produced from unsubstituted phenyl alpha-maltoside (øM) or p-tert-butylphenyl alpha-maltoside (PTBøM) was a mixture of alpha- and beta-anomers, the ratio being dependent on pH as follows: For øM, the percentage of alpha-anomer was 100% (pH 5.4), 80 (pH 6.18), and 55% (pH 6.73), whereas for PTBøM, the percentage of beta-anomer was 100% (pH 5.4), 75% (pH 6.18), and 60% (pH 6.73).