Forms of vitamin B12 compounds containing sulfitoB12 in corbiculas

Forms of vitamin B12 (B12) compounds in young and aged corbiculas were examined by bioautography using B12-requiring microorganisms combined with cellulose acetate membrane electrophoresis or high-performane liquid chromatography (HPLC). Both corbiculas (per 100 g) contained ca. 30 microg of cobalamin, a complete type of B12. Five known B12 compounds, adenosylB12 (AdoB12), methylB12, hydroxoB12, sulfitoB12 and cyanoB12, were identified by bioautography. Young corbicula contained more B12 compounds, assumed as methylB12, AdoB12 and sulfitoB12, as compared to aged corbicula. All of the B12 compounds detected around the location corresponding to those of methylB12, AdoB12 and sulfitoB12 in the bioautography were converted into compounds that behaved like hydroxoB12 after photolysis. Young corbicula was found to contain an unidentified B12 compound using bioautography combined with HPLC. A large portion of the B12 compound that moved like hydroxoB12 during cellulose acetate membrane electrophoresis using 0.5 N acetic acid might be identical with the unidentified B12 compound detected in the HPLC-bioautography.