Self-association of Zn-insulin at neutral pH: investigation by concentration gradient--static and dynamic light scattering.
Equilibrium self-association of Zn-insulin at pH 7.0 was characterized over the range 0.3-5mg/mL by simultaneous measurement of static and dynamic light scattering. Analysis of static light scattering yielded a concentration-dependent weight-average molecular weight, and analysis of dynamic light scattering yielded a concentration-dependent intensity-average diffusion coefficient. The concentration dependence of both quantities may be accounted for to within experimental precision by a simple model, according to which the basic structural unit of Zn-insulin at concentrations exceeding 0.3mg/mL is a hexamer H. With increasing total protein concentration, hexameric protomers may self-associate in accordance with an isodesmic scheme in which a protomer may add to any prexisting oligomer H(n) to form H(n+1) with an invariant stepwise equilibrium association constant.
Attri
Arun K
AK
National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, MD 20892, USA. attri@mail.jnu.ac.in
Fernández
Cristina
C
Minton
Allen P
AP
D000818:Animals; D002417:Cattle; D002850:Chromatography, Gel; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000737:chemistry* / Q000378:metabolism*; D008027:Light; D009994:Osmolar Concentration; D011485:Protein Binding; D012542:Scattering, Radiation; D012996:Solutions; D015032:Zinc / Q000737:chemistry
D007328:Insulin; D012996:Solutions; D015032:Zinc