The degradation of radioiodinated alpha MSH in vitro: effect of some inhibitors of proteolytic enzymes]

The velocity of labelled alpha MSH degradation by rat tissues has been studied at different temperatures. The appearance of damaged compounds from 125I alpha MSH is much lower at 4 degrees C than at 22 or 37 degrees C. The addition of proteolysis inhibitors (benzamidine or zymofren) reduces the damage velocity. Under standard conditions of temperature and buffer, the damage velocity is lower when the tissue homogenates are processed by heat (56 degrees C; 40 min.). The existence of an enzymatic system capable of degradating radioiodine alpha MSH in the rat brain is discussed.