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The X-ray three-dimensional structure of avidin.
C Rosano1, P Arosio, M Bolognesi
1Centro Biotecnologie Avanzate-IST and Dipartimento di Fisica-INFM, University of Genova, Italy.
Biomolecular Engineering
|May 5, 2000
Summary
Avidin, a protein from egg white, binds biotin with exceptionally high affinity. Its stable structure, characterized by beta-barrels, explains this strong molecular interaction.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Science
Background:
- Avidin is a homotetrameric protein found in bird egg-white.
- It exhibits high stability and binds D-biotin with extremely high affinity (Kd ~10^-15 M).
- Avidin shares structural and functional similarities with sretpavidin.
Purpose of the Study:
- To investigate the structural basis of D-biotin binding in avidin.
- To understand the molecular mechanisms behind avidin's high affinity for D-biotin.
- To compare avidin's structure with related proteins like sretpavidin.
Main Methods:
- Crystallographic investigations of avidin.
- Analysis of avidin crystal structures.
- Structural comparison between avidin and sretpavidin.
Main Results:
- Avidin subunits exhibit near-exact 222 symmetry in crystal structures.
- Each subunit consists of an eight-stranded antiparallel beta-barrel forming the D-biotin binding site.
- The binding site is rigid, sterically complementary, and accessible, explaining the high affinity for D-biotin.
Conclusions:
- The structural features of avidin, particularly its beta-barrel binding site, are crucial for its high affinity to D-biotin.
- Avidin's structure provides a molecular explanation for its strong interaction with the vitamin.
- Avidin and sretpavidin demonstrate significant structural and functional conservation.