The structure of the complex between avidin and the dye, 2-(4'-hydroxyazobenzene) benzoic acid (HABA)

Oded Livnah, Edward A. Bayer, Meir Wilchek, Joel L. Sussman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

57 Scopus citations


The crystal structure of the complex formed between the egg-white biotin-binding protein, avidin, and the dye, 2-(4'-hydroxyazobenzene) benzoic acid (HABA), was determined to a resolution of 2.5 A. The interaction of avidin with the benzoate ring of HABA is essentially identical to that of the complex formed between HABA and streptavidin (the bacterial analogue of the egg-white protein). This interaction emulates the definitive high-affinity interaction of both proteins with the ureido moiety of biotin. The major difference between the avidin- and streptavidin-HABA complexes lies in their interaction with the hydroxyphenyl ring of the dye molecule; in avidin, two adjacent amino acid residues (Phe72 and Ser73), which are not present in streptavidin, form additional interactions with this ring. These are suggested to account for the higher affinity of avidin for HABA. The characteristic red shift, which accompanies the interaction of both proteins with the dye, was traced to a proposed charge-transfer complex formed between the hydroxyphenyl ring of HABA and the indole ring of Trp70 in avidin (Trp79 in streptavidin). Comparison of binding site residues of two such similar proteins versus their markedly different affinities for two such different substrates should eventually contribute to a better design of biomimetic reagents and drugs.

Original languageAmerican English
Pages (from-to)165-168
Number of pages4
JournalFEBS Letters
Issue number1-2
StatePublished - 9 Aug 1993
Externally publishedYes

Bibliographical note

Funding Information:
Ackno,lle~~emel~tsW. e thank G. Shoham and 2. Greenblat from the Hebrew University of Jerusalem for their help in data collectlon on the R-AXIS-II IP System. Parts of this work were supported by the Basic Research Foundation, administered by The Israel Academy of Sciences and Humamties. and by the Helen and MIlton A. Klmmel-man Center for Biomolecular Structure and Assembly of the Werzmann Institute of Science.


  • Avidin
  • Biomimetics
  • Biotin-binding site
  • HABA
  • Protein structure
  • Streptavidin
  • X-ray crystallography


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