The production of magnesium protoporphyrin monomethyl ester by Rhodopseudomonas spheroides.

A monoester of magnesium protoporphyrin has been isolated by Granick (1961) from a chlorophyll-less mutant of Chlorella and from etiolated barley leaves treated with 8-aminolaevulic acid and aaoc-bipyridyl. It was considered likely that this material was a methyl ester that Granick then proposed as an intermediate in the biosynthesis of chlorophyll. The extraction from Rhodop8eudomona spheroides of an enzyme system which methylates magnesium protoporphyrin to form the monomethyl ester (Tait & Gibson, 1961) has been given as evidence for the participation of this metalloporphyrin in bacteriochlorophyll biosynthesis. In this paper is described the detection and identification of magnesium protoporphyrin monomethyl ester, which was secreted into the medium by intact cells of R. spheroide8, growing on complete medium and carrying out normal bacteriochlorophyll synthesis.