In this study, intensity of ANS (1-Anilino-8-Naphtalen Sulfunate) fluorescence at 480nm has been taken as a measure of the amount of hCG (Human Chorionic Gonadotropinr) in the solution. The rate of subunit dissociation of hCG has been turned out to be as a first order reaction in the range of pH=2 to 10 at different temperature. The dissociation rate constant in acid medium is higher than in other mediums. Gel filtration study has shown that the elution volume of hCG decreases as the pH decreases. Sodium Dodecyl Sulfate (SDS) slows down the subunit dissociation of hCG through the concentration range used. The best inhibitory concentration of SDS is found to be 0.7mM. The activation energies increase, in all pH in the presence of SDS. The maximum value of activation energies are corresponding to the concentration of 0.7mM of SDS. It has been evident that the gel filtration causes, in all pH and the presence of SDS (0.7 mM), the increase of elution volume of hCG. The decrease in the rate of subunit dissociation in addition to the increase in activation energy in the presence of SDS could be accounted for the partial folding of hCG.

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