RESUMO
The effect of alkaline pH on sunflower 11S protein has been monitored by the techniques of ultracentrifugation, polyacrylamide gel electrophoresis, turbidity, viscosity, ultraviolet absorption spectra and fluorescence spectra· Both ultracentrifugation and polyacrylamide gel electrophoresis show the dissociation of the protein with increase in pH. Turbidity values decrease with pH while viscosity increases· With increase in pH absorbance of the protein solution increases and there is a red shift in the absorption maximum. Fluorescence quenching and a red shift in the emission maximum are also observed. Both dissociation and denaturation of the protein occur. Analysis of turbidity, viscosity and fluorescence data suggests that apparently denaturation follows dissociation.
RESUMO
The effect of sodium dodecyl sulphate, urea or guanidinium hydrochloride on the sedimentation velocity, viscosity, ultra violet spectra and fluorescence spectra of the 11S protein of guar seed has been determined. Sodium dodecyl sulphate dissociates the protein directly to the 2S protein, whereas urea or guanidinium hydrochloride produces an intermediate 7S protein. These reagents denature the protein also. Both the dissociative and the denaturation effect follow the order, sodium dodecyl sulphate > guanidinium hydrochloride > urea when the concentration are expressed as mols per litre. The denatured states in the three cases probably differ.
RESUMO
The effect of sodium dodecyl sulphate, urea, guanidinium hydrochloride and heat on the oligomeric structure of the 11 S protein of sunflower has been determined. Sodium dodecyl sulphate directly dissociates the protein to 2 S subunits, whereas urea and guanidinium hydrochloride dissociate it through an intermediate 7 S protein. Heating the protein at 90°C for 20 min caused dissociation of the 11 S protein, without any precipitation.