Biosynthesis of 5,6-dimethylbenzimidazole from [1'-14C,5-15N]6,7-dimethyl-8-ribityllumazine

Lu, Sheue-Hon; Alworth, William L.

doi:10.1021/bi00754a021

Cited by 2 publications

(2 citation statements)

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“…It has been established that the C-2 carbon atom of DBI is derived biosynthetically from the V-C atom of the ribityl side chain of V (Alworth et al, 1971;Lu and Alworth, 1972) and of riboflavin (Renz and Weyhenmeyer, 1972) (cf. Figure 1).…”

Section: Discussionmentioning

confidence: 99%

“…Investigations carried out in our laboratory (Alworth et al, 1969, 197 Í; Lu and Alworth, 1972) and those of Renz (Renz and Reinhold, 1967;Renz, 1970;Kühnle and Renz, 1971;Renz and Weyhenmeyer, 1972) have established a biosynthetic relationship between riboflavin and the 5,6-dimethylbenzimidazole (DBI)* 1 component of vitamin B¡2. Indeed, evidence suggests that riboflavin is an obligatory intermediate in the biosynthesis of DBI (Renz, 1970;Renz and Weyhenmeyer, 1972; see also discussion in Plaut et al, 1974).…”

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confidence: 97%

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Biosynthesis of the dimethylbenzene moiety of riboflavin and dimethylbenzimidazole: evidence for the involvement of C-1 of a pentose as a precursor

Alworth¹,

Dove²,

Baker³

1977

Biochemistry

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The relative incorporations of specially labeled pyruvate, lactate, erythritol, D-erythrose, D-ribose, and D-glucose precursors into the dimethylbenzene carbon atoms of the 5,6-dimethylbenzimidazole unit of vitamin B12 by Propionibacterium shermanii have been determined. The incorporation data provide information regarding the putative four-carbon biosynthetic unit which is involved in the formation of 6,7-dimethyl-8-ribityllumazine and which is the source of the eight dimethylbenzene carbon atoms of both 5,6-dimethylbenzimidazole and riboflavin. The relative incorporations of the labeled lactate and pyruvate precursors are not consistent with either acetoin or 2,3-butanedione functioning as the four-carbon biosynthetic unit. The relative incorporations of the labeled hexose, pentose, and tetrose precursors indicate that the observed incorporation of C-1 of the pentose into the dimethylbenzene carbon atoms does not involve metabolism to a tetrose intermediate, but occurs more directly. It is concluded that the C-1 position of a pentose precursor is involved in the formation of the putative four-carbon biosynthetic unit.

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Section: Discussionmentioning

confidence: 99%