OXIDATION OF METHIONINE RESIDUES IN EQUINE GROWTH-HORMONE BY CHLORAMINE-T

1. Reactivity of methionine residues towards Chloramine-T was studied in the equine growth hormone. 2. With a 20.0-fold molar excess of reag ent over methionine, full oxidation of the four residues of the protei n is achieved. 3. Methionine 4 is the most reactive group, followed by methionines 72 and 178-methionine 123 being the less reactive residue . 4. As judged by circular dichroism spectra and binding assays, prote in conformation and binding capacity to specific receptors remains unc hanged even after full oxidation of all four methionine residues. 5. R esults agree with data previously obtained with bovine growth hormone.