期刊
BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS
卷 1794, 期 4, 页码 709-715出版社
ELSEVIER
DOI: 10.1016/j.bbapap.2008.12.017
关键词
alpha-Lactalbumin; Lysozyme; Interaction; Heterodimer; Fluorescence
资金
- French National Research Agency
- Agence Nationale de la Recherche [ANR-07PNRA-010]
In a previous work, we reported that contrary to native calcium-loaded a-lactalbumin (holo (X-LA), calcium-depleted form (apo alpha-LA) has the ability to self-assemble with lysozyme (LYS) to form different supramolecular structures in temperature-dependent manner. In this study, we examine what happens at molecular scale using fluorescence techniques. Fluorescence anisotropy coupled with fluorescence lifetime measurements provides a means to measure intermolecular interactions. We showed that LYS interacts with both apo alpha-LA and holo alpha-LA to form oligomers, assumed to be heterodimers, at 10 degrees C and 45 degrees C. The dissociation constants for dimerization were found to be in the mu M range and increased significantly with increasing ionic strength from 39 to 124 mM. Although the binding constants of holo alpha-LA-LYS and apo alpha-LA-LYS complexes were of the same order of magnitude, the shape or conformation of formed heterodimers differed as assessed by fluorescence parameters in particular correlation time calculations. Such conformation differences could explain why holo a-LA-LYS complexes are trapped as heterodimers while the apo alpha-LA-LYS complexes have the ability to further self-assemble into various supramolecular structures. (C) 2008 Elsevier B.V. All rights reserved.
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