Format

Send to

Choose Destination
See comment in PubMed Commons below
Biochem J. 1996 May 15;316 ( Pt 1):193-9.

Reversibility of biotin-binding by selective modification of tyrosine in avidin.

Author information

1
Department of Membrane Research and Biophysics, Weizmann Institute of Science, Rehovot, Israel.

Abstract

The tight interaction between the vitamin biotin and the protein avidin is so strong (Ka approximately 10(15) M-1) that conditions which are usually sufficient for protein denaturation fail to dissociate the avidin-biotin complex. In order to form a reversible interaction between the two biomolecules, we have modified the binding-site tyrosine by nitration, thus reducing the pKa of the phenol group which forms a crucial hydrogen bond with the ureido group of biotin. At relatively low pH values (4-5), the resultant modified forms of avidin bind biotin with a very high association constant ( > 10(9) M-1). The modified avidins are thus capable of supporting stable, long-term binding of biotin or biotinylated macro-molecules. The latter molecules can be detached by increasing the pH of the medium or by introduction of excess levels of biotin at neutral pH. These findings demonstrate the importance of a single hydrogen bond for strong biotin binding. The new derivatives of avidin should be useful for applications whereby a reversible interaction between the four biotin-binding sites and biotin is desired, thus increasing the versatility of the avidin-biotin system for biotechnological application.

PMID:
8645205
PMCID:
PMC1217322
[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Support Center