Rathnam P, Saxena BB. Studies on modification of tryptophan, methionine, tyrosine and arginine residues of human follicle-stimulating hormone and its subunits.
BIOCHIMICA ET BIOPHYSICA ACTA 1979;
576:81-7. [PMID:
367446 DOI:
10.1016/0005-2795(79)90486-0]
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Abstract
Based on the regeneration of the hormonal activity following recombination, the alpha and beta subunits of human follicle-stimulating hormone have been designated as 'functional' or 'nonfunctional'. Chemical modifications of the tryptophan, methionine, tyrosine and arginine residues of human follicle-stimulating hormone, luteinizing hormone, and the 'functional' human follicle-stimulating hormone alpha and beta subunits have indicated that the tryptophan in human follicle-stimulating hormone-beta and human luteinizing hormone-beta is essential for the biological activity. The iodination of human follicle-stimulating hormone-alpha did not interfere with the hormonal activity. The modification of arginine abolishes the biological activity of the hormones. The accessibility of tyrosine and methionine in human follicle-stimulating hormone-alpha, of arginine in both native hormones and subunits, and the non-availability of the tryptophan residues to 2-hydroxy 5-nitrobenzyl bromide suggest that the alpha subunit lies on the surface of the native molecule.
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