Biochemical investigations on prolidase and prolinase in erythrocytes from patients with prolidase deficiency

Abstract

Prolidase (EC 3.4.13.9) deficiency is a rare autosomal recessive disease affecting the degradation of collagen associated with chronic ulcerative dermatities, mental retardation and massive urinary excretion of iminodipeptides [l-lo]. Prolidase deficiency can be diagnosed by the assay of prolidase activity in erythrocytes [11,12], leucocytes [3] and cultured skin fibroblasts [4,9,11]. These reports have utilized Gly-Pro as the substrate and indicated almost complete deficiency of the enzyme. Butterworth et al has recently reported that prolidase in cultured skin fibroblasts from the patient is altered rather than absent, such that activity against Gly-Pro is very low, but only moderately reduced against other substrates [13,14] and separated two peaks by DEAE-cellulose ion-exchange chromatography [15]. We described in previous papers biochemical aspects and dermatological features from two siblings with prolidase deficiency and massive excretion of iminodipeptides [5,7,9]. The older sister presented the typical clinical symptoms of the desease, but the younger sister developed no clinical symptoms. The relationships between prolidase deficiency and the clinical manifestations are yet unknown. The present investigation shows several characteristics of prolidase and prolinase (EC 6.4.13.8) in erythrocytes from two siblings with prolidase deficiency, then parents and controls subjects.