Strong impact of ionic strength on the kinetics of fibrilar aggregation of bovine β-lactoglobulin

被引:65
作者
Arnaudov, Luben N.
de Vries, Renko
机构
[1] Wageningen Univ, Lab Phys Chem & Colloid Sci, NL-6700 EK Wageningen, Netherlands
[2] Wageningen Univ, Food Phys Grp, NL-6703 HD Wageningen, Netherlands
关键词
D O I
10.1021/bm060584i
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
We investigate the effect of ionic strength on the kinetics of heat-induced fibrilar aggregation of bovine beta-lactoglobulin at pH 2.0. Using in situ light scattering we find an apparent critical protein concentration below which there is no significant fibril formation for all ionic strengths studied. This is an independent confirmation of our previous observation of an apparent critical concentration for 13 mM ionic strength by proton NMR spectroscopy. It is also the first report of such a critical concentration for the higher ionic strengths. The critical concentration decreases with increasing ionic strength. Below the critical concentration mainly "dead-end" species that cannot aggregate anymore are formed. We prove that for the lowest ionic strength this species consists of irreversibly denatured protein. Atomic force microscopy studies of the morphology of the fibrils formed at different ionic strengths show shorter and curvier fibrils at higher ionic strength. The fibril length distribution changes non-monotonically with increasing ionic strength. At all ionic strengths studied, the fibrils had similar thicknesses of about 3.5 nm and a periodic structure with a period of about 25 nm.
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页码:3490 / 3498
页数:9
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