Fig. 1.

Oxidative branch of the chloroplast‐localized pentose phosphate pathway (in orange) carrying anaplerotic carbon flux into the Calvin–Benson cycle (in grey). Blue and green, enzyme reactions that may introduce deuterium fractionation signals at glucose H¹ and H², respectively. Dashed arrows, intermediate reactions not shown. Enzymes, G6PD, glucose‐6‐phosphate dehydrogenase; PGI, phosphoglucose isomerase. Metabolites: 3PGA, 3‐phosphoglycerate; 6PG, 6‐phosphogluconate; 6PGL, 6‐phosphogluconolactone; ATP, adenosine triphosphate; F6P, fructose 6‐phosphate; G6P, glucose 6‐phosphate; NADPH, nicotinamide adenine dinucleotide phosphate; Ru5P, ribulose 5‐phosphate; RuBP, ribulose 1,5‐bisphosphate; TP, triose phosphates (glyceraldehyde 3‐phosphate, dihydroxyacetone phosphate). Modified figure from Wieloch et al. (2022).