Growth of Paracoccus denitrificans on [2, 3- 13 C]succinate and [1, 4- 13 C]succinate IIl. Biosynthetic pathways

The biosynthesis in vivo of a number of amino acids, sugars, and purines in Paracoccus denitrificans grown on either [2, 3- 13 C]succinate or [1, 4- 13 C]succinate was investigated by using gas chromatography–mass spectrometry. The distribution of label in the TCA-cycle-related amino acids indicated that carbon intermediates of energy metabolism were utilized as precursors for the biosynthesis of these amino acids in vivo . The biosynthesis of glycine, serine, phenylalanine and glycerol from labelled succinate in vivo were consistent with phosphoenol pyruvate as an intermediate. A mechanism for the formation of C 4 , C 5 and C 6 sugars without the use of fructose-1, 6-bisphosphate aldolase (which has not been detected in P. denitrificans ) is proposed. The 13 C-enrichments of ribose in the bacterium indicate that there are at least three routes of ribose biosynthesis operating during growth on labelled succinate. The probability distribution of labelled purine molecules was successfully predicted for adenine, guanine and adenosine, thus confirming their generally accepted route of biosynthesis in vivo .