Structural changes in calcium-binding allergens: use of circular dichroism to study binding characteristics
Article first published online: 2 AUG 2005
Volume 60, Issue 9, pages 1208–1211, September 2005
How to Cite
Hebenstreit, D. and Ferreira, F. (2005), Structural changes in calcium-binding allergens: use of circular dichroism to study binding characteristics. Allergy, 60: 1208–1211. doi: 10.1111/j.1398-9995.2005.00907.x
- Issue published online: 2 AUG 2005
- Article first published online: 2 AUG 2005
- Accepted for publication 26 April 2005
- Bet v 4;
- circular dichroism
Background: Several studies showed that calcium-binding proteins have a fixed place in the spectrum of allergenic substances. Often the binding of a calcium ion induces conformational changes and affects immunoglobulin E-binding to the allergen. Hence, the quantitative characterization of the binding to calcium is of importance to understand both the biologic and allergenic activity of these proteins.
Aims of the study: In the present study we describe a procedure for determining the stoichiometry and dissociation constant (KD) of calcium-binding allergens using circular dichroism (CD) techniques. For the experiments, we used recombinant Bet v 4, a two EF-hand allergen from birch pollen.
Methods: Solutions of Bet v 4 were titrated with calcium and the change in molar ellipticity at 222 nm was monitored with a CD spectropolarimeter.
Results: The determination of the binding stoichiometry as well as of the KD for one EF-hand (4 μM) demonstrated the applicability of the method.
Conclusions: CD-monitored calcium-titration of protein solutions represents a fast and easy method for determining the binding characteristics of calcium-binding allergens.