Secondary Nucleation and Accessible Surface in Insulin Amyloid Fibril Formation
- 1 March 2008
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry B
- Vol. 112 (12), 3853-3858
- https://doi.org/10.1021/jp710131u
Abstract
At low pH insulin is highly prone to self-assembly into amyloid fibrils. The process has been proposed to be affected by the existence of secondary nucleation pathways, in which already formed fibrils are able to catalyze the formation of new fibrils. In this work, we studied the fibrillation process of human insulin in a wide range of protein concentrations. Thioflavin T fluorescence was used for its ability to selectively detect amyloid fibrils, by mechanisms that involve the interaction between the dye and the accessible surface of the fibrils. Our results show that the rate of fibrillation and the Thioflavin T fluorescence intensity saturate at high protein concentration and that, surprisingly, the two parameters are proportional to each other. Because Thioflavin T fluorescence is likely to depend on the accessible surface of the fibrils, we suggest that the overall fibrillation kinetics is mainly governed by the accessible surface, through secondary nucleation mechanisms. Moreover, a statistical study of the fibrillation kinetics suggests that the early stages of the process are affected by stochastic nucleation events.Keywords
This publication has 49 references indexed in Scilit:
- Amyloid fibrils formation and amorphous aggregation in concanavalin ABiophysical Chemistry, 2007
- Thermal induced conformational changes involved in the aggregation pathways of beta-lactoglobulinBiophysical Chemistry, 2005
- Principles of protein folding, misfolding and aggregationSeminars in Cell & Developmental Biology, 2004
- Aggregation kinetics of bovine serum albumin studied by FTIR spectroscopy and light scatteringBiophysical Chemistry, 2003
- Conformational changes involved in thermal aggregation processes of bovine serum albuminBiophysical Chemistry, 2003
- Protein folding and misfolding: a paradigm of self–assembly and regulation in complex biological systemsPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2003
- The behaviour of polyamino acids reveals an inverse side chain effect in amyloid structure formationThe EMBO Journal, 2002
- Conformational Prerequisites for α-Lactalbumin FibrillationBiochemistry, 2002
- Designing conditions for in vitro formation of amyloid protofilaments and fibrilsProceedings of the National Academy of Sciences, 1999
- Kinetic studies on photolysis-induced gelation of sickle cell hemoglobin suggest a new mechanismBiophysical Journal, 1980