Enzymatic heterogeneity of seminomas.

Heterogeneity of placental-like alkaline phosphatase (PLAP-like enzyme) in seminoma was studied. PLAP-like enzyme from seminoma tissues was separated into three areas with different proportions between tumors, while PLAP and PLAP-like enzymes in normal testes were separated into two areas on the basis of hydrophobicity. By use of lectin affinity chromatography, PLAP-like enzyme in seminoma revealed extra sugar chains compared to PLAP, indicating heterogeneity of the carbohydrate moiety. However, the glycosylation patterns were found to be essentially similar between seminoma and normal testis. On isoelectric focusing, differences in migration patterns of PLAP-like enzyme were revealed between seminoma and normal testis as well as between PLAP-like enzyme and PLAP. The differences in charge were mainly due to differences in sialylation of the molecules. The complex pattern on isoelectric focusing was not altered by neuraminidase treatment, indicating a considerable charge heterogeneity within the population of PLAP-like enzyme molecules from seminoma.