MRG-001

A Gram-negative anaerobic microorganism, MRG-1, isolated from human intestine showed high activities of deglycosylation and reduction of daidzin, based on rapid TLC analysis. A rod-shaped strain MRG-1 was identified as a new species showing 91.0% homology to Coprobacillus species, based on 16S rRNA sequence analysis. The strain MRG-1 showed β-glucosidase activity toward daidzin and genistin, and daidzein and genistein were produced, respectively. However, the strain MRG-1 did not react with flavone glycosides, flavanone glycosides, and isoflavone C-glucoside. Besides, MRG-1 showed stereoselective reductase activity to isoflavone, daidzein, genistein, 7-hydroxyisoflavone, and formononetin, resulting in the formation of corresponding R-isoflavanone enantiomers. The new isoflavanones of 7-hydroxyisoflavanone and dihydroformononetin were characterized by NMR, and the absolute configurations of the enantiomers were determined with CD spectroscopy. The kinetic study of the anaerobic biotransformation showed both activities were exceptionally fast compared to the reported conversion by other anaerobic bacteria.

A monoclonal antibody, MRG‐1, was produced by immunizing a mouse with a human ovarian mucinous cyst adenocarcinoma‐derived cell line, RMUG‐L. By immunohistochemical staining, the antigen was found to be exclusively localized in the intracellular structures of the cells used as the antigen and of the epithelial cells in normal human cervical glands. However, although the antigen was predominantly detected in the plasma membrane and the intercellular structure of the middle layer of normal human cervical squamous epithelium (92%), it was also contained in the intracellular structure of cervical epidermal carcinoma at a high frequency (80%). The striking difference in the distribution of the MRG‐1 antigen between normal and cancerous tissues was found to be a cervical carcinoma‐associated phenomenon and a useful tumor marker for immunohistochemical examination. Since the antigen was found to be of a blood group A‐related nature by immunohistochemical staining of the tissues and to be a glycosphingolipid, it was purified from human erythrocytes of blood group A, and the structure was concluded to be GalNAcα1–3Gal(2–1αFuc)jβ1–3GalNAcα1–3Gal(2–1αFuc)‐ β1–4GlcNAcβ1–3Galβl‐4Glcβ1–1′Cer, blood group A type 3 chain‐containing glycosphingolipid, by NMR, negative ion FABMS and permethylation analysis. In the subcellular localization analysis of the antigen, type 3‐A glycosphingolipid antigen was detected in the Golgi body and the microsomes of RMUG‐L cells, and the distribution coincided with the finding by immunohistochemical staining. In addition, in cervical epidermal carcinoma, although the blood group A, mainly type 2‐A chain, was localized in the plasma membrane and the intercellular structure, the blood group A type 3 chain was selectively found in the perinuclear structure. Also, the blood group A type 3 chain in cervical dysplasia as well as that in normal cervix was predominant in the plasma membrane. Thus, the selective intracellular localization of blood group A type 3 chain was a phenomenon characteristic of cervical epidermal carcinoma and the carcinoma in situ.