Abstract
During the course of studies on purine-corrinoids and their coenzyme-forms with Propionibacterium arabinosum, a variety of intermediates were obtained depending upon the conditions for the biosynthesis. The relation between the chemical structures of the intermediates as well as the products and the conditions for the biosynthesis suggested that Pr.arabinosum have an additional pathway of corrinoid biogenesis to the same two as Pr.shermanii except for the ability to synthesize organic bases. The addition of excessive base, even if of appropriate nature for incorporation into corrin ring, resulted in accumulation of corrinoid-carboxylic acids as well as incomplete corrinoids as their coenzyme forms. The finding suggests that the biosynthesis of corrinoid-molecule might proceed as its coenzyme-form, which seems to be formed at the same time or soon after incorporation of Co-atom into corrin ring followed by the ring closure.
