Effects of glycine hydroxamate, carbon dioxide, and oxygen on photorespiratory carbon and nitrogen metabolism in spinach mesophyll cells
The effects of added glycine hydroxamate on the photosynthetic incorporation of /sup 14/CO/sub 2/ into metabolites by isolated mesophyll cells of spinach (Spinacia oleracea L.) was investigated under conditions favorable to photorespiratory (PR) metabolism (0.04% CO/sub 2/ and 20% O/sub 2/) and under conditions leading to nonphotorespiratory (NPR) metabolism (0.2% CO/sub 2/ and 2.7% O/sub 2/). Glycine hydroxamate (GH) is a competitive inhibitor of the photorespiratory conversion of glycine to serine, CO/sub 2/ and NH/sub 4//sup +/. During PR fixation, addition of the inhibitor increased glycine and decreased glutamine labeling. In contrast, labeling of glycine decreased under NPR conditions. This suggests that when the rate of glycolate synthesis is slow, the primary route of glycine synthesis is through serine rather than from glycolate. GH addition increased serine labeling under PR conditions but not under NPR conditions. This increase in serine labeling under PR conditions but not under NPR conditions. This increase in serine labeling at a time when glycine to serine conversion is partially blocked by the inhibitor may be due to serine accumulation via the ''reverse'' flow of photorespiraton from 3-P-glycerate to hydroxypyruvate when glycine levels are high. GH increased glyoxylate and decreased glycolate labeling. These observations are discussed with respect to possible glyoxylate feedback inhibition of photorespiration.
- Research Organization:
- Univ. of California, Berkeley, CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5148766
- Journal Information:
- Plant Physiol.; (United States), Vol. 69
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON 14 COMPOUNDS
METABOLISM
CARBON DIOXIDE
BIOLOGICAL EFFECTS
HYDROXAMIC ACIDS
NITROGEN
OXYGEN
RESPIRATION
INHIBITION
AMINO ACIDS
PHOTOSYNTHESIS
PLANT CELLS
SPINACH
AMINES
CARBON COMPOUNDS
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
FOOD
HYDROXY COMPOUNDS
LABELLED COMPOUNDS
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
SYNTHESIS
VEGETABLES
550201* - Biochemistry- Tracer Techniques
551001 - Physiological Systems- Tracer Techniques
550301 - Cytology- Tracer Techniques