Effect of Aggregation on the Hydrodynamic Properties of Bovine Serum Albumin.
PURPOSE
To systematically analyze shape and size of soluble irreversible aggregates and the effect of aggregate formation on viscosity.


METHODS
Online light scattering, refractive index and viscosity detectors attached to HPLC (Viscotek®) were used to study aggregation, molecular weight and intrinsic viscosity of bovine serum albumin (BSA). Irreversible aggregates were generated by heat stress. Bulk viscosity was measured by an oscillating piston viscometer.


RESULTS
As BSA was heated at a higher concentration or for a longer time, the relative contribution, molecular weight and intrinsic viscosity of aggregate species increased. Molecular shape was evaluated from intrinsic viscosity values, and aggregates were estimated to be more asymmetric than monomer species. The presence of aggregates resulted in an increase in bulk viscosity when relative contribution of very high molecular weight species exceeded 10%.


CONCLUSIONS
For model system and conditions studied, generation of higher order aggregate species was concluded to be associated with an increase in molecular asymmetry. Elevated viscosity in the presence of aggregated species points to molecular asymmetry being a critical parameter affecting solution viscosity of BSA.
['Pindrus|Mariya A|MA|', 'Cole|James L|JL|', 'Kaur|Japneet|J|', 'Shire|Steven J|SJ|', 'Yadav|Sandeep|S|', 'Kalonia|Devendra S|DS|']
D000818:Animals D002417:Cattle D002851:Chromatography, High Pressure Liquid D000067493:Dynamic Light Scattering D006358:Hot Temperature D057446:Hydrodynamics D006863:Hydrogen-Ion Concentration D015394:Molecular Structure D008970:Molecular Weight D066329:Protein Aggregates D012031:Refractometry D012710:Serum Albumin, Bovine D014783:Viscosity
aggregation intrinsic viscosity effective molecular shape