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Light scattering and viscosity study of heat aggregation of insulin
Author(s) -
Bohidar Himadri B.
Publication year - 1998
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/(sici)1097-0282(199801)45:1<1::aid-bip1>3.0.co;2-x
Subject(s) - chemistry , radius of gyration , hydrodynamic radius , intrinsic viscosity , viscosity , thermodynamics , intermolecular force , diffusion , aqueous solution , dynamic light scattering , light scattering , solvent , atmospheric temperature range , static light scattering , reduced viscosity , analytical chemistry (journal) , scattering , polymer , chromatography , molecule , organic chemistry , physics , nanoparticle , optics , micelle , quantum mechanics
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 20–40°C 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 [η], diffusion coefficient D 0 , molecular weight M , and radius of gyration R g exhibited the universal behavior: M [η] = (2.4 ± 02) × 10 −27 ( R e,η /R e,D ) 3 ( D 0η / T ) −3 and ( D 0 √ n ) −1 ≃ (√6 πη 0 ζβ/ k B T ) [1 + 0.201)( v /β 3 )√ n ], where n is the number of segments in the polypeptide. The effective hydrodynamic radii deduced from [η], ( R e , η) and the same deduced from D 0 , ( R e,D ) showed a constant ratio, ( R e,η / R e,D = 1.1 ± 0.1). R e,D / R g = ξ was found to be (0.76 ± 0.07). From the known solvent viscosity η 0 , the segment length β was deduced to be (10 ± 1) Å. The excluded volume was deduced to be (5 Å) 3 regardless of pH. The Flory‐Huggins interaction parameter was found to be χ = 0.45 ± 0.04, independent of pH and temperature. © 1998 John Wiley & Sons, Inc. Biopoly 45: 1–8, 1998