Demonstration of glucose‐6‐phosphate hydrogen 5 enrichment from deuterated water by transaldolase‐mediated exchange alone

Abstract

Hydrogen 5 of G6P was enriched from (2)H2O through exchanges mediated by transaldolase. These studies prove that G6P can be enriched in hydrogen 5 by (2)H2O independently of gluconeogenesis.

Metabolic incorporation of H218O into specific glucose‐6‐phosphate oxygens by red‐blood‐cell lysates as observed by 13C isotope‐shifted NMR signals

“…Following evaporation of the ethyl acetate, MAG was further purified using a 500 mg Discovery DSC‐18 (Supelco®, Sigma‐Aldrich®, St. Luis, MO, USA) solid‐phase extraction column, being eluted with 10% ACN. The lyophilized purified residue was dissolved in 200 μL of deuterated water for 13 C NMR analysis 14 …”

“…hydrogens that had undergone exchange with water via the same enzymatic steps approached that of the aqueous medium. 14…”

“…[11][12][13] Previously, we utilized this experiment to characterize deuterium incorporation from deuterated water into various positions of glucose-6-phosphate, with derivatization to monoacetone glucose (MAG) to provide full resolution of positional deuterium enrichment information. 14 In this study, we applied the same approach to determine enrichment of the six carbon-bound oxygens of glucose-6-phosphate from H 2 18 O. Based on these previous hemolysate studies, where sugar phosphate exchanges are dominated by phosphoglucoisomerase, triose phosphate isomerase, aldolase and transaldolase, 11-14 18 O is predicted to be highly incorporated into Positions 1, 2, 4 and 5 (see Figure 1).…”

“…O in this setting as a means of determining fractional rates of exchange or turnover is entirely dependent on a natural-abundance 13 C reporter nucleus, whereas 2 H can be observed either independently of 13 C enrichment 14,25 or via fully resolved isotope shifts and/or coupling interactions with adjacent 13 C nuclei. 26,27 Therefore, compared with 2 H 2 O, the scope for integrating NMR measurements of metabolite enrichment from H 2…”

Disposition of a Glucose Load into Hepatic Glycogen by Direct and Indirect Pathways in Juvenile Seabass and Seabream

“…Therefore, both oxidative and non-oxidative PPP activity will alter glycogen enrichment distributions from 2 H- and 13 C-tracers. Such activity is revealed most clearly in the 13 C-isotopomer data 42 , 43 . In the absence of PPP flux, the 13 C-isotopomers derived from indirect pathway metabolism have identical distributions in the 123- and 456- carbons of glycogen.…”