Studies on the biotin-binding site of streptavidin. Tryptophan residues involved in the active site.
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Gitlin G, Bayer EA, Wilchek M
Studies on the biotin-binding site of streptavidin. Tryptophan residues involved in the active site.
Biochem J. 1988 Nov 15;256(1):279-82.
- PubMed ID
- 3223904 [ View in PubMed]
- Abstract
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.