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. 1973 Jun;51(6):1051–1054. doi: 10.1104/pp.51.6.1051

Enzymatic Fractionation of Carbon Isotopes by Phosphoenolpyruvate Carboxylase from C4 Plants 1

Tom Whelan a, W M Sackett a, C R Benedict b
PMCID: PMC366402  PMID: 16658463

Abstract

The carbon atoms of glucose and malate in C4 plants are 2 to 3‰ enriched in 12C with respect to atmospheric CO2; whereas these intermediates in C3 plants are 15 to 18‰ enriched with 12C with respect to atmospheric CO2. The enzymatic synthesis of malate from phosphoenolpyruvate and bicarbonate in preparations of leaves of Sorghum bicolor, Haygrazer result in a carbon isotope fractionation of about 3‰. The enzymatic synthesis of phosphoglyceric acid from ribulose 1,5-diP and CO2 in these preparations (contaminated with carbonic anhydrase) at 24 C and 37 C result in a carbon isotope fractionation of 33.7‰ and 18.3‰, respectively. These data are consistent with the conclusion that the small enrichment of 12C in the carbon atoms of malate and glucose (with respect to atmospheric CO2) in leaves of Sorghum bicolor, Haygrazer occurs at the phosphoenolpyruvate carboxylase step.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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