Fujimori H, Ohnishi M, Hiromi K
J Biochem. 1978 May;83(5):1503-10. doi: 10.1093/oxfordjournals.jbchem.a132060.
Four tryptophan residues of saccharifying alpha-amylase from B. subtilis out of eleven in total are reactive towards N-bromosuccinimide (NBS), suggesting that they are on the surface of the enzyme. This is consistent with the results of solvent perturbation difference spectrophotometry with ethylene glycol. One of four tryptophan residues was clearly distinguished from the other three in reactivity with NBS by the stopped-flow method. This most reactive tryptophan residue was not protected from modification by substrates of analogs, indicating that the tryptophan is not located in the substrate binding site. One of the other three tryptophan residues, probably the second most reactive one, is considered to be related in some way to the glycosyl transfer in the reaction of the enzyme with maltose as a substrate.
枯草芽孢杆菌糖化α-淀粉酶总共11个色氨酸残基中的4个对N-溴代琥珀酰亚胺（NBS）有反应，这表明它们位于酶的表面。这与用乙二醇进行的溶剂扰动差示分光光度法的结果一致。通过停流法，4个色氨酸残基中的1个在与NBS的反应性上与其他3个明显不同。这个反应性最强的色氨酸残基不受底物类似物修饰的保护，表明该色氨酸不在底物结合位点。其他3个色氨酸残基中的1个，可能是反应性第二强的那个，被认为在某种程度上与该酶以麦芽糖为底物的反应中的糖基转移有关。
