Present status of the zinc glycinate marker (ZGM).

ZGM was purified from both primary and metastatic colonic carcinomas demonstrably positive for ZGM by immunofluorescence microscopy. ZGM purification included preparative Pevikon electrophoresis, Sepharose 4B molecular exclusion chromatography and Con A-Sepharose affinity chromatography. ZGM had an alpha2 electrophoretic mobility, an estimated molecular weight by Sepharose 4B equal to or greater than 2 x 10(6), and did not bind to Con A-Sepharose, although having determinants with CEA-like activity. Its immunologic activity was resistant to trypsin or phospholipase A but not to neuraminidase. Antisera prepared to ZGM and absorbed with saliva, when tested by double immunodiffusion, formed a single precipitation line with saline extracts of colon tumors and did not cross-react with CEA, AFP, normal tissue extracts, ferritin, NCA, NCA-2, CSAp, blood groups A, B, H, Lewis antigen, or buffy coat, alpha-2 macroglobulin, saliva or ovarian cyst fluid. Immunofluorescence microscopy confirmed the presence of ZGM in 40 out of 45 adenocarcinomas of the GI tract staining primarily in tumors, the apical cytoplasm, and in grossly nonmalignant tissues, the deep crypts of the villi, while all of 22 non-GI tumors in the study were ZGM negative.