Studies on the 4-carbon precursor in the biosynthesis of riboflavin. Purification and properties of L-3,4-dihydroxy-2-butanone-4-phosphate synthase.
The formation of the riboflavin precursor, 6,7-dimethyl-8-ribityllumazine, from 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione requires a phosphorylated 4-carbon intermediate which has been designated as Compound X (Neuberger, G., and Bacher, A. (1985) Biochem. Biophys. Res. Commun. 127, 175-181). The enzyme catalyzing the formation of Compound X has been purified about 600-fold from the cell extract of the flavinogenic yeast Candida guilliermondii by chromatographic procedures. The purified protein appeared homogeneous as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and consisted of a single polypeptide of 24 kDa. The committed substrate of the enzyme was identified as D-ribulose 5-phosphate. The enzyme yields two products which were identified as L-3,4-dihydroxy-2-butanone 4-phosphate and formate by NMR and CD spectroscopy. Mg2+ is required for activity.
Volk
R
R
Lehrstuhl für Organische Chemie und Biochemie, Technische Universität München, Garching, Federal Republic of Germany.
Bacher
A
A
D002175:Candida / Q000201:enzymology*; D002845:Chromatography; D002942:Circular Dichroism; D004798:Enzymes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D005561:Formates / Q000378:metabolism; D019751:Intramolecular Transferases; D008274:Magnesium / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D008970:Molecular Weight; D011498:Protein Precursors / Q000096:biosynthesis*; D011621:Pteridines / Q000378:metabolism*; D012256:Riboflavin / Q000096:biosynthesis*; D012274:Ribulosephosphates / Q000378:metabolism; D013379:Substrate Specificity; D013403:Sugar Phosphates / Q000096:biosynthesis*
D004798:Enzymes; D005561:Formates; D011498:Protein Precursors; D011621:Pteridines; D012274:Ribulosephosphates; D013403:Sugar Phosphates; C030544:formic acid; C066494:3,4-dihydroxy-2-butanone-4-phosphate; C031524:ribulose 5-phosphate; C001061:6,7-dimethyl-8-ribityllumazine; D019751:Intramolecular Transferases; C066493:L-3,4-dihydroxy-2-butanone-4-phosphate synthase; D008274:Magnesium; D012256:Riboflavin