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.
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Research Article| November 15 1988
Studies on the biotin-binding site of streptavidin. Tryptophan residues involved in the active site
E A Bayer;
Biochem J (1988) 256 (1): 279–282.
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G Gitlin, E A Bayer, M Wilchek; Studies on the biotin-binding site of streptavidin. Tryptophan residues involved in the active site. Biochem J 15 November 1988; 256 (1): 279–282. doi: https://doi.org/10.1042/bj2560279
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