The identification of a sugar derived from coenzyme B12.

The structure of coenzyme Biz has been shown to be based upon that of vitamin Blz (1). The main structural differences between the coenzyme and the vitamin are the absence of cyanide and the presence of an adenine nucleoside in the coenzyme. An adenine nucleoside was isolated after photolysis of the coenzyme (2, 21). Although the photolysis reaction is complex and gives rise to two colorless ultraviolet-absorbing compounds, the adenine nucleoside (peak 1 photolysis product) is generally the more abundant. Mild acid hydrolysis of the coenzyme yields adenine and a sugarlike compound. Adenine was identified by its ultraviolet absorption spectrum, its chromatographic and ionophoretic behavior (2), and by preparation of its picrate (3). Further elucidation of the structure of the cobamide coenzymes requires the identification of the sugar-like compound formed by acid hydrolysis. This paper describes the characterization of this compound as D-erythro-2,3-dihydroxy-A4-pentenal.