Oxygen-17 appears only in protein in water-stressed soybean leaves labeled by (17)O2.
We have used a rotational-echo adiabatic-passage double-resonance (13)C{(17)O} solid-state NMR experiment to prove that the glycine produced in the oxygenase reaction of ribulose bisphosphate carboxylase-oxygenase is incorporated exclusively into protein (or protein precursors) of intact, water-stressed soybean leaves exposed to (13)CO(2) and (17)O(2). The water stress increased stomatal resistance and decreased gas exchange so that the Calvin cycle in the leaf chloroplasts was no more than 35% (13)C isotopically enriched. Labeled O(2) levels were sufficient, however, to increase the (17)O isotopic concentration of oxygenase products 20-fold over the natural-abundance level of 0.04%. The observed direct incorporation of glycine into protein shows that water stress suppresses photorespiration in soybean leaves.
Gullion
Terry
T
Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, USA.
Yu
Tsyr-Yan
TY
Singh
Manmilan
M
Patti
Gary J
GJ
Potter
Gregory S
GS
Schaefer
Jacob
J
D055162:Biocatalysis; D002245:Carbon Dioxide / Q000737:chemistry; D005998:Glycine / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D010100:Oxygen / Q000737:chemistry; D010103:Oxygen Isotopes / Q000737:chemistry; D010105:Oxygenases / Q000737:chemistry* / Q000378:metabolism; D018515:Plant Leaves / Q000201:enzymology* / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000737:chemistry* / Q000378:metabolism; D013025:Glycine max / Q000201:enzymology* / Q000378:metabolism; D014867:Water / Q000737:chemistry
D010103:Oxygen Isotopes; D014867:Water; D002245:Carbon Dioxide; D010105:Oxygenases; D012273:Ribulose-Bisphosphate Carboxylase; D010100:Oxygen; D005998:Glycine