Light scattering and viscosity study of heat aggregation of insulin

✍ Scribed by Himadri B. Bohidar

• Publisher: Wiley (John Wiley & Sons)
• Year: 1998
• Tongue: English
• Weight: 96 KB
• Volume: 45
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/(sici)1097-0282(199801)45:1<1::aid-bip1>3.0.co;2-x

✦ Synopsis

Aggregation behavior and hydrodynamic parameters of insulin have been determined from static and dynamic light scattering experiments and intrinsic viscosity measurements carried out at pH 4.0, 7.5, and 9.0 in the temperature range 20-40ЊC in aqueous solutions. The protein aggregated extensively at elevated temperatures in the acidic solutions. Intermolecular interactions were found to be attractive and to increase with temperature. The measured intrinsic viscosity [h], diffusion coefficient D 0 , molecular weight M, and radius of gyration R g exhibited the universal behavior:

where n is the number of segments in the polypeptide. The effective hydrodynamic radii deduced from [h], (R e , h) and the same deduced from D 0 , (R e, D ) showed a constant ratio, (R e,h /R e, D Å 1.1 { 0.1). R e, D /R g Å j was found to be (0.76 { 0.07). From the known solvent viscosity h 0 , the segment length b was deduced to be (10 { 1) A ˚. The excluded volume was deduced to be (5 A ˚)3 regardless of pH. The Flory-Huggins interaction parameter was found to be x Å 0.45 { 0.04, independent of pH and temperature.