Characteristics of Partially Purified Prolidase from Erythrocytes of Normal Individuals, of Two Patients with Prolidase Deficiency, and of the Patients⁵ Mother

Two forms of prolidase could be separated by TSK DEAE-5PW chromatography from erythrocytes of normal subjects and from those of the mother of two patients with prolidase deficiency. Only one form of prolidase was separated from erythrocytes of the patients with prolidase deficiency. Each peak (I and II) of prolidase differed in its response to Mn²⁺, substrate specificity, and heat stability. Prolidase activity in erythrocytes from the patients showed a complete lack of peak I of normal prolidase, whereas peak II had normal activity against all the substrates tested. Molecular weights of partially purified prolidases I and II from normal erythrocytes were about 110,000 and 185,000 daltons, respectively and that of the prolidase from erythrocytes of the patients, 185,000 daltons. The various properties between patients' prolidase and peak II of normal prolidase were very similar. The activity of peak I from erythrocytes of the patients' mother was reduced about 50% compared with that of normal individuals, but activity of peak II was almost the same. These results suggest that for at least the present two cases, the lower prolidase activity seen in erythrocytes from patients with prolidase deficiency results from lack of the peak I enzyme rather than from an alteration of normal prolidase.