Decarboxylation of glycine contributes to carbon isotope fractionation in photosynthetic organisms
2001 (English)In: Photosynthesis Research, ISSN 0166-8595, E-ISSN 1573-5079, Vol. 67, no 3, 177-184 p.Article in journal (Refereed) Published
Carbon isotope effects were investigated for the reaction catalyzed by the glycine decarboxylase complex (GDC; EC 22.214.171.124). Mitochondria isolated from leaves of pea (Pisum sativum L.) and spinach (Spinacia oleracea L.) were incubated with glycine, and the CO2 evolved was analyzed for the carbon isotope ratio (delta C-13). Within the range of parameters tested (temperature, pH, combination of cofactors NAD(+), ADP, pyridoxal 5-phosphate), carbon isotope shifts of CO2 relative to the C-1-carboxyl carbon of glycine varied from +14 parts per thousand to -7 parts per thousand. The maximum effect of cofactors was observed for NAD(+), the removal of which resulted in a strong C-12 enrichment of the CO2 evolved. This indicates the possibility of isotope effects with both positive and negative signs in the GDC reaction. The measurement of delta C-13 in the leaves of the GDC-deficient barley ( Hordeum vulgare L.) mutant (LaPr 87/30) plants indicated that photorespiratory carbon isotope fractionation, opposite in sign when compared to the carbon isotope effect during CO2 photoassimilation, takes place in vivo. Thus the key reaction of photorespiration catalyzed by GDC, together with the key reaction of CO2 fixation catalyzed by ribulose-1,5-bisphosphate carboxylase, both contribute to carbon isotope fractionation in photosynthesis.
Place, publisher, year, edition, pages
2001. Vol. 67, no 3, 177-184 p.
carbon isotope fractionation, glycine decarboxylase, photorespiration, photorespiratory mutants, plant mitochondria
IdentifiersURN: urn:nbn:se:umu:diva-44658ISI: 000169520600002OAI: oai:DiVA.org:umu-44658DiVA: diva2:434113