T. Fujita, M. Ohata, H. Orimo
Jun 1, 1969
The kidney was reported to be the main site of parathyroid hormone inactivation in rats (Orimo et al., 1 965a). Such inactivation is apparently carried out by some heat labile, pH dependent principle inhibited by proteinase inhibitors (Orimo et al., 1965b). Vajda et al. (1969) introduced the use of 125 I-labeled parathormone in studies on the hydrolysis of this hormone. Martin et al.(1969) demonstrated degradation of 125 I-labeled parathormone by a rat kidney enzyme. Since the nature of such enzyme(s) which are responsible for parathormone degradation still remains obscure, we have studied the optimum pH, organ and subcellular distribution, substrate specificity, and effect of various enzyme inhibitors and metal ions in order to define the mechanism of such degradation more precisely.