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The redox levels and subcellular distribution of pyridine nucleotides in illuminated barley leaf protoplasts studied by rapid fractionation
Author(s) -
Wigge Bosse,
Krömer Silke,
Gardeström Per
Publication year - 1993
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1993.tb01754.x
Subject(s) - photorespiration , nad+ kinase , biochemistry , hordeum vulgare , glycine , redox , chemistry , cytosol , serine , oxidative phosphorylation , biology , photosynthesis , enzyme , amino acid , botany , poaceae , organic chemistry
The redox level and compartmentation of pyridine nucleotides was studied under photorespiratory and non‐photorespiratory conditions using rapid fractionation of barley ( Hordeum vulgare L. cv. Gunilla, Svalöv) leaf protoplasts. From comparative measurements of the NADPH/NADP + ratio and the ATP/ADP ratio one acidic and one alkaline extraction medium was chosen which quenched the metabolism very efficiently. The mitochondrial NADH/NAD + was higher under photorespiratory conditions than under non‐photorespiratory conditions. Aminoacetonitrile, an inhibitor of the photorespiratory conversion of glycine to serine, lowered the mitochondrial NADH/NAD + ratio. This supports the hypothesis that glycine oxidation is coupled to oxidative phosphorylation to provide ATP to the cytosol. The chloroplastic NADPH/NADP + as well as the NADH/NAD + ratios were quite stable in saturating and limiting CO 2 as well as in the presence of aminoacetonitrile, although the triosephosphate/phosphoglycerate ratios changed. Thus, the redox level in the stroma seems to be tightly regulated.