Purification and properties of 3-hexulosephosphate synthase from Methylomonas M 15.
3-Hexulosephosphate synthase, the first enzyme of the ribulose monophosphate cycle, was purified 15-fold from methanol-grown Methylomonas M 15. The purification procedure involved chromatography on DEAE-cellulose, Sephadex G-75, and DEAE-Sephadex A-50. The purified enzyme was more than 95% pure as judged by analytical polyacrylamide gel electrophoresis. The molecular weight was calculated to be 43000 from sedimentation equilibrium experiments. Electrophoresis in sodium dodecylsulfate gels gave a single band corresponding to a molecular weight of 22000. The enzyme catalyzes specifically the condensation formaldehyde with ribulose 5-phosphate to yield D-arabino-3-hexulose 6-phosphate. The Km values were found to be 1.1 mM for formaldehyde and 1.6 mM for ribulose 5-phosphate. A bivalent cation is essential for activity and stability of the enzyme, Mg2+ and Mn2+ serve best for this purpose. The optimum of pH for enzyme activity is 7.5--8.0.
D000446:Aldehyde-Lyases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D002413:Cations, Divalent; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008772:Methylococcaceae / Q000201:enzymology*; D008970:Molecular Weight; D010428:Pentosephosphates / Q000378:metabolism; D013329:Structure-Activity Relationship
D002413:Cations, Divalent; D010428:Pentosephosphates; D008345:Manganese; D000446:Aldehyde-Lyases; C021355:hexose phosphate synthetase; D008274:Magnesium