Gitlin G, Bayer E A, Wilchek M
Department of Biophysics, Weizmann Institute of Science, Rehovot, Israel.
Biochem J. 1988 Nov 15;256(1):279-82. doi: 10.1042/bj2560279.
Streptavidin, the non-glycosylated bacterial analogue of the egg-white glycoprotein avidin, was modified with the tryptophan-specific reagent 2-hydroxy-5-nitrobenzyl (Hnb) bromide. As with avidin, complete loss of biotin-binding activity was achieved upon modification of an average of one tryptophan residue per streptavidin subunit. Tryptic peptides obtained from an Hnb-modified streptavidin preparation were fractionated by reversed-phase h.p.l.c., and three major Hnb-containing peptide fractions were isolated. Amino acid and N-terminal sequence analysis revealed that tryptophan residues 92, 108 and 120 are modified and probably comprise part of the biotin-binding site of the streptavidin molecule. Unlike avidin, the modification of lysine residues in streptavidin failed to result in complete loss of biotin-binding activity. The data imply subtle differences in the fine structure of the respective biotin-binding sites of the two proteins.
链霉抗生物素蛋白是蛋清糖蛋白抗生物素蛋白的非糖基化细菌类似物，用色氨酸特异性试剂2-羟基-5-硝基苄基（Hnb）溴化物进行修饰。与抗生物素蛋白一样，每个链霉抗生物素蛋白亚基平均修饰一个色氨酸残基后，生物素结合活性完全丧失。从Hnb修饰的链霉抗生物素蛋白制剂中获得的胰蛋白酶肽通过反相高效液相色谱进行分级分离，分离出三个主要的含Hnb肽级分。氨基酸和N端序列分析表明，色氨酸残基92、108和120被修饰，可能构成链霉抗生物素蛋白分子生物素结合位点的一部分。与抗生物素蛋白不同，链霉抗生物素蛋白中赖氨酸残基的修饰并未导致生物素结合活性完全丧失。数据表明这两种蛋白质各自生物素结合位点的精细结构存在细微差异。
