Related Experiment Videos
The Ca2+-binding sequence in bovine brain S100b protein beta-subunit. A spectroscopic study.
1Laboratoire de Physique, Faculté de Pharmacie, Université Louis Pasteur, Strasbourg, France.
The Biochemical Journal
|November 15, 1989
Summary
Calcium binding to S100-beta protein causes sequential conformational changes. The second calcium ion binding significantly alters the protein structure, affecting tyrosine fluorescence and absorption properties.
Area of Science:
- Biochemistry
- Molecular Biology
- Protein Structure
Background:
- S100-beta is a calcium-binding protein found in bovine brain.
- Understanding its conformational changes upon calcium binding is crucial for elucidating its function.
Purpose of the Study:
- To investigate the conformational changes in S100-beta upon calcium binding.
- To analyze the spectroscopic properties of tyrosine residue (Tyr17 beta) and binding interactions.
Main Methods:
- Spectroscopic analysis of Tyr17 beta.
- Flow-dialysis binding experiments.
- Fluorescence and circular dichroism (c.d.) measurements.
Main Results:
- S100-beta binds Ca2+ sequentially at two sites, altering protein conformation.
- The second Ca2+ binding strengthens a hydrogen bond involving Tyr17 beta, significantly changing its fluorescence and absorption spectra.
- Zinc ions enhance Ca2+ affinity but do not alter the binding sequence.
- Terbium ions selectively antagonize Ca2+ binding site II beta.
Conclusions:
- Ca2+ binding induces sequential conformational changes in S100-beta, with the N-terminal site occupancy causing significant structural alterations.
- The study provides insights into the Ca2+-binding mechanism and structural dynamics of S100-beta.