Circular dichroism studies of sheep beta-lipotropic hormone.
The far ultraviolet circular dichroism spectra of sheep beta-lipotropic hormone (beta-LPH) were recorded under different conditions of pH, temperature, salt concentration, and solvent composition. Results confirm the stability of the hormone in strong basic or acidic solutions; moreover, temperatures up to 50 degrees C do not seem to affect noticeably the conformation of beta-LPH. However, increasing the NaC1 concentration or addition of dioxane in the solution brings about a conformational transition of the chain, interpreted as an increase in the helical content. The method of Yang (Chen, Y.H., Yang, J. T. &amp; Martinez, H. M. (1972) Biochemistry 11, 4120-4131) was used to compute the proportion of helical, beta, and unordered forms of the hormone chain. The proportions are compared with those obtained from Fasman's predictive method (Chou, P. Y &amp; Fasman, G. D. (1974) Biochemistry 13, 211-221 and Chou, P. Y. &amp; Fasman, G. D. (1974) Biochemistry 13, 222-245) based on the known amino acid sequence of beta-LPH.
Circular dichroism studies of sheep beta-lipotropic hormone. The far ultraviolet circular dichroism spectra of sheep beta-lipotropic hormone (beta-LPH) were recorded under different conditions of pH, temperature, salt concentration, and solvent composition. Results confirm the stability of the hormone in strong basic or acidic solutions; moreover, temperatures up to 50 degrees C do not seem to affect noticeably the conformation of beta-LPH. However, increasing the NaC1 concentration or addition of dioxane in the solution brings about a conformational transition of the chain, interpreted as an increase in the helical content. The method of Yang (Chen, Y.H., Yang, J. T. &amp; Martinez, H. M. (1972) Biochemistry 11, 4120-4131) was used to compute the proportion of helical, beta, and unordered forms of the hormone chain. The proportions are compared with those obtained from Fasman's predictive method (Chou, P. Y &amp; Fasman, G. D. (1974) Biochemistry 13, 211-221 and Chou, P. Y. &amp; Fasman, G. D. (1974) Biochemistry 13, 222-245) based on the known amino acid sequence of beta-LPH.