STUDIES ON MODIFICATION OF TRYPTOPHAN, METHIONINE, TYROSINE AND ARGININE RESIDUES OF HUMAN FOLLICLE-STIMULATING-HORMONE AND ITS SUBUNITS

Based on the regeneration of the hormonal activity following recombination, the α and β 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 α and β subunits have indicated that the tryptophan in human follicle-stimulating hormone-β and human luteinizing hormone-β is essential for the biological activity. The iodination of human follicle-stimulating hormone-α 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-α, 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 α subunit lies on the surface of the native molecule. © 1979.