[On cobyrinic acid biosynthesis. Novel methylated hydroporphyrins and their role in cobyrinis acid formation (author's transl)]

Abstract

Clostridium tetanomorphum and Propionibacterium shermanii were examined for intermediates in the synthetic pathway uroporphyrinogen III leads to cobyrinic acid. The isolation of two novel methylated hydroporphyrins, whose methyl groups are derived from S-adenosyl-L-methionine, is described. Spectroscopic (field desorption-mass, visible absorption) und electrophoretic studies as well as incorporation of labelled substrates indicate that they are analogues of a dihyrouroporphyrin and a tetrahydrouroporphyrin with adjacent reduced rings. Field desorption spectra of the [C2H3]- and [CH3]-tetrahydrouroporphyrin analogues show that the compound contains two methyl groups; it is concluded that the chlorine-like compound has one methyl group. Dehydrogenation experiments indicate that the methyl groups are located at one beta-carbon of the reduced rings. Incorporation experiments suggest that the tetrahydrouroporphyrin-like compound is an intermediate in cobyrinic acid biosynthesis. Studies on the utilization of a heptacarboxyporphyrinogen from C. tetanomorphum for cobyrinic acid formation are also described.