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[14] Enzymic synthesis of13C-enriched aldoses, ketoses, and their phosphate esters

1982; Academic Press; Linguagem: Inglês

10.1016/s0076-6879(82)89016-2

1557-7988

Anthony S. Serianni, E. Cadman, John P. Pierce, Michael L. Hayes, R. Barker,

Metabolism and Genetic Disorders

This chapter describes the enzymic synthesis of 13C-enriched aldoses, ketoses, and their phosphate esters. The carbohydrates with isotopic enrichment at specific sites are prepared by enzymic modification of chemically synthesized precursors. The method for preparing isotopically enriched aldoses or aldose phosphates is extended to prepare ketoses or ketose phosphates using commercially available enzymes and substrates, such as adenosine triphosphate (ATP). Dihydroxyacetone phosphate (DHAP) is prepared enzymically from dihydroxyacetone and ATP by the action of glycerol kinase. The 13C-enriched starting material for D-[4-13C] fructose and D-[4-13C] glucose conversion is DL-[1-13C] glyceraldehyde, which is prepared by the condensation of K13CN with glycolaldehyde, followed by the hydrogenation and solvolysis of the nitrile product. The sequential action of phosphoriboisomerase and phosphoribulokinase on D-[2-13C] ribose 5-phosphate gives D-[2-13C] ribulose 1,5-bisphosphate in 85% overall yield. D-[2-13C] ribose 5-P is prepared from D-[1-13C] erythrose-4-P and KCN. The enzymes of the glycolytic pathway—hexokinase, phosphoglucose isomerase, and phosphofructokinase—are used to convert D- [2-13C] glucose to D-[2-13C] fructose 1,6-bisphosphate in 86% yield. The addition of aldolase and triosephosphate isomerase, or extended incubation with aldolase, gives D-fructose 1,6-bisphosphate in which the 13C isotope is symmetrically distributed.