Effects of aminoacetonitrile on net photosynthesis, ribulose-1,5-bisphosphate levels, and glycolate pathway intermediates
The effects of aminoacetonitrile (a competitive inhibitor of glycine oxidation) on net photosynthesis, glycolate pathway intermediates, and ribulose-1,5-bisphosphate (RuBP) levels have been investigated at different O/sub 2/ and CO/sub 2/ concentrations with soybean leaf discs floated on 25 millimolar aminoacetonitrile (AAN) for 50 minutes prior to assay. At 11% to 60% O/sub 2/, AAN caused a decrease in net photosynthesis in addition to the inhibition by O/sub 2/. This extra inhibition ranged from 22% to 59% depending on the O/sub 2/ and CO/sub 2/ concentrations. The levels of RuBP, however, were 1.3 to 2.7 times higher than in the control plants at the same O/sub 2/ concentrations . At 40% O/sub 2/ and 200 microliters per liter CO/sub 2/ the inhibitor caused a 6-fold increase in glycine and more than 2-fold increase in glyoxylate levels, whereas those of glycolate decreased by approximately one-half. The decrease in net photosynthesis observed with AAN is not the result of the depletion of the RuBP pool due to the lack of recycling of carbon from the glycolate pathway to the Calvin cycle. The higher levels of RuBP caused by AAN in photorespiratory conditions, suggest that RuBP carboxylase was inhibited. Glyoxylate could be a possible candidate for the inhibition of the enzyme but what is know so far about its inhibitory properties in vitro may not fit the existing in vivo conditions. An alternative explanation for the inhibition is proposed.
- Research Organization:
- Iowa State Univ., Ames
- DOE Contract Number:
- AC02-80ER10685
- OSTI ID:
- 6656926
- Journal Information:
- Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 70; ISSN PLPHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
560301* -- Chemicals Metabolism & Toxicology-- Cells-- (-1987)
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOCHEMISTRY
BIOLOGICAL EFFECTS
CARBOHYDRATES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
ELEMENTS
FOOD
GLYCOLYSIS
KETONES
LEAVES
MONOSACCHARIDES
NITRILES
NONMETALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PENTOSES
PHOSPHATES
PHOSPHORUS COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
RIBULOSE
SACCHARIDES
SOYBEANS
SYNTHESIS
VEGETABLES