title: Activity and subcellular localization of glucose-6-phosphate dehydrogenase in peach fruits.
abstract: The subcellular distribution and activity of glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) were studied in developing peach (Prunus persica L. Batsch cv. Zaoyu) fruit. Fruit tissues were separated by differential centrifugation at 15,000g into plastidic and cytosolic fractions. There was no serious loss of enzyme activity (or activation) during the preparation of fractions. G6PDH activity was found in both the plastidic and cytosolic compartments. Moreover, DTT had no effect on the plastidic G6PDH activities, that is, the redox regulatory mechanism did not play an important role in the peach fleshy tissue. Results from the immunogold electron-microscope localization revealed that G6PDH isoenzymes were mainly present in the cytosol, the secondary wall and plastids (chloroplasts and chromoplasts), but scarcely found in the starch granules or the cell wall. In addition to a decrease in fruit firmness, the G6PDH activity in the cytotolic and plastidic fractions increased, and anthocyanin started to accumulate during fruit maturation. These results suggest that G6PDH, by providing precursors for metabolic processes, might be associated with the red coloration that occurs in peach fruit.
authors.affiliation: College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, PR China.
authors.forename: Wei-Fu
authors.initials: WF
authors.lastname: Kong
authors.forename: Jian-Ye
authors.initials: JY
authors.lastname: Chen
authors.forename: Zhi-Xia
authors.initials: ZX
authors.lastname: Hou
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Wen
authors.forename: Ji-Cheng
authors.initials: JC
authors.lastname: Zhan
authors.forename: Qiu-Hong
authors.initials: QH
authors.lastname: Pan
authors.forename: Wei-Dong
authors.initials: WD
authors.lastname: Huang
mesh_terms: D000872:Anthocyanins / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure; D004229:Dithiothreitol / Q000494:pharmacology; D005419:Flavonoids / Q000378:metabolism; D005638:Fruit / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D005954:Glucosephosphate Dehydrogenase / Q000032:analysis / Q000378:metabolism*; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000032:analysis / Q000378:metabolism; D010940:Plant Proteins / Q000032:analysis / Q000378:metabolism*; D018087:Plastids / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure; D027861:Prunus / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure
chemical_list: D000872:Anthocyanins; D005419:Flavonoids; D007527:Isoenzymes; D010940:Plant Proteins; D005954:Glucosephosphate Dehydrogenase; D004229:Dithiothreitol