Enhanced incorporation of tritium into glycolate during photosynthesis by tobacco leaf tissue in the presence of tritiated water
Tobacco (Nicotiana tabacum var. Havana Seed) leaf discs were allowed to photosynthesize for 3 to 20 minutes in the present of /sup 14/CO/sub 2/ and /sup 3/H/sub 2/O. Several metabolites of the Calvin cycle and photorespiratory pathway were isolated and purified and the /sup 3/H:/sup 14/C values measured. Glycolate had a 5- to 10-fold higher /sup 3/H:/sup 14/C than the Calvin cycle intermediate 3- phosphoglyceric acid, or its end product sucrose. The glycolate oxidase inhibitor ..cap alpha..-hydroxy-2-pyridinemethanesulfonic acid caused glycolate to accumulate in the tissue and lowered the /sup 3/H:/sup 14/C in glycolate to a value similar to that in 3-phosphoglyceric acid. Phosphoglycolate, a possible precursor of glycolate arising from the Calvin cycle, exhibited a /sup 3/H:/sup 14/C value similar 3-phosphoglyceric acid under all conditions. The finding of a /sup 3/H enrichment in glycolate suggests that another source of glycolate, possibly the reduction of glyoxylate, exists in leaf tissue. Analyses of incorporation of /sup 3/H into the pro-2R and pro-2S hydrogens of glycolate, in the presence and absence of ..cap alpha..-hydroxy-2-pyridinemethanesulfonic acid, suggest an alternative source of glycolate. Biochemical mechanisms to account for /sup 3/H enrichment into glycolate are evaluated.
- Research Organization:
- The Connecticut Agricultural Experiment Station, New Haven
- OSTI ID:
- 5734082
- Journal Information:
- Plant Physiol.; (United States), Vol. 69:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
METABOLITES
BIOLOGICAL PATHWAYS
NICOTIANA
PHOTOSYNTHESIS
CARBON 14 COMPOUNDS
CARBON DIOXIDE
GLYCOLIC ACID
LEAVES
SCINTISCANNING
TRACER TECHNIQUES
TRITIUM COMPOUNDS
WATER
CARBON COMPOUNDS
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
COUNTING TECHNIQUES
DIAGNOSTIC TECHNIQUES
HYDROGEN COMPOUNDS
HYDROXY ACIDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PLANTS
RADIOISOTOPE SCANNING
SYNTHESIS
550501* - Metabolism- Tracer Techniques