Table of Contents
Journal of Biophysics
Volume 2012 (2012), Article ID 434289, 7 pages
http://dx.doi.org/10.1155/2012/434289
Research Article

Inhibitory Effects of Arginine on the Aggregation of Bovine Insulin

The Department of Physics and Astronomy, Union College, Schenectady, NY 12308, USA

Received 5 April 2012; Revised 28 May 2012; Accepted 5 June 2012

Academic Editor: Peter Schuck

Copyright © 2012 Michael M. Varughese and Jay Newman. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Static and dynamic light scattering were used to investigate the effects of L-arginine, commonly used to inhibit protein aggregation, on the initial aggregation kinetics of solutions of bovine insulin in 20% acetic acid and 0.1 M NaCl as a model system for amyloidosis. Measurements were made as a function of insulin concentration (0.5–2.0 mM), quench temperature (60–85°C), and arginine concentration (10–500 mM). Aggregation kinetics under all conditions had a lag phase, whose duration decreased with increasing temperature and with increasing insulin concentration but which increased by up to a factor of 8 with increasing added arginine. Further, the initial growth rate after the lag phase also slowed by up to a factor of about 20 in the presence of increasing concentrations of arginine. From the temperature dependence of the lag phase duration, we find that the nucleation activation energy doubles from 1 7 ± 5 to 3 6 ± 3  kcal/mol in the presence of 500 mM arginine.