Isoelectric focusing of alpha-L-fucosidase from human embryonal carcinoma

Isoelectric focusing profiles of alpha-L-fucosidase recovered from human embryonal carcinoma (EC) and seminoma were compared with those of mouse germ cell tumor-derived stem cells and some human somatic cell neoplasms in an attempt to determine whether EC cells could be used as a source of human basic isoelectric forms of the enzyme previously identified in normal and malignant mouse embryonic cells. alpha-L-Fucosidase activity in all human tumors was associated with isoelectric forms in the isoelectric point (pl) range between approximately 4.5 and 7, corresponding to the range seen in normal human tissues. The basic isoelectric forms (pl values, 7.5-9.5) that predominate in the embryonic isoelectric focusing pattern in mouse were not found in human neoplasms. The present data illustrate another difference between human and mouse EC and show that mouse EC cells are not a complete replica of equivalent human tumor cells.