Genov N, Shopova M, Boteva R, Jori G, Ricchelli F
Biochem J. 1982 Nov 1;207(2):193-200. doi: 10.1042/bj2070193.
Circular-dichroism and fluorescence studies indicate that the 5-dimethylaminonaphthalene-1-sulphonyl and phenylmethanesulphonyl derivatives of subtilisin DY have three-dimensional structure closely similar to that of native enzyme. The single tryptophan residue is largely accessible to the aqueous solvent, and is not directly involved in the enzyme-substrate interactions, since its photochemical modification causes only a partial inhibition of the enzyme activity. It appears very likely that the location of the single tryptophan residue in the three-dimensional structure of subtilisin DY is similar to that of the single tryptophan residue in subtilisin Carlsberg. Fluorescence-quenching experiments further indicate that the 14 tyrosine residues are also largely accessible to the aqueous solvent, and probably interact with hydrated peptide carbonyl groups. The charge environment for tryptophan and tyrosine residues in subtilisin DY, as deduced by quenching experiments with ionic species, is also discussed. In general, subtilisin DY displays strong similarities to subtilisin Carlsberg, as suggested by a comparative analysis of the amino acid composition and fluorescence properties.
圆二色光谱和荧光研究表明，枯草杆菌蛋白酶DY的5-二甲基氨基萘-1-磺酰基和苯甲磺酰基衍生物具有与天然酶非常相似的三维结构。单一色氨酸残基在很大程度上可接触到水性溶剂，且不直接参与酶与底物的相互作用，因为其光化学修饰仅导致酶活性部分受到抑制。很有可能枯草杆菌蛋白酶DY三维结构中单一色氨酸残基的位置与枯草杆菌蛋白酶Carlsberg中单一色氨酸残基的位置相似。荧光猝灭实验进一步表明，14个酪氨酸残基在很大程度上也可接触到水性溶剂，并且可能与水合肽羰基相互作用。还讨论了通过离子物种猝灭实验推断出的枯草杆菌蛋白酶DY中色氨酸和酪氨酸残基的电荷环境。总体而言，正如氨基酸组成和荧光特性的比较分析所表明的那样，枯草杆菌蛋白酶DY与枯草杆菌蛋白酶Carlsberg表现出很强的相似性。
