Characteristics of prolidase and prolinase in prolidase-deficient patients with some preliminary studies of their role in skin

1) The prolidase (Pd) and prolinase (Pn) activities of cultured skin fibroblasts derived from two prolidase-deficient sisters, the elder with typical clinical manifestations [symptom (+)] and the younger with only slight clinical manifestations [symptom (-)] were examined biochemically. Pd activity against several substrates other than Gly-Pro were present to some degree in both sisters. There were no detectable differences in Pd activity between the symptom (+) patient and the symptom (-) sister. Pn activity seemed to be increased in both. The lower Pn activity found against Pro-Gly as compared with those against other substrates indicates that Pro-Gly, which has been used for Pn assays in most previous reports, may not be the best substrate for this test. Pd derived from control fibroblasts was activated by Mn²⁺ against all substrates tested in this experiment. Cu²⁺, Hg²⁺, Cd²⁺ and Zn²⁺ remarkably inhibited enzyme activity, Co²⁺ slightly inhibited it, and neither Mg²⁺ nor Fe²⁺ had any remarkable effect. The Pd derived from the prolidase-deficient patients was also activated by Mn²⁺. This Pd seemed to be more inhibited by Co²⁺ than was the control. However, we found no remarkable differences between the two patients. 2) We also studied Pd and Pn activities in rat skin and blood during wound healing. Pd and Pn activities adjacent to the wound increased in parallel with fibroblast proliferation. Pd activity was also detected in an extract of newborn mouse epidermis.