title: Ripening of pepper (Capsicum annuum) fruit is characterized by an enhancement of protein tyrosine nitration.
abstract: OBJECTIVE
  Pepper (Capsicum annuum, Solanaceae) fruits are consumed worldwide and are of great economic importance. In most species ripening is characterized by important visual and metabolic changes, the latter including emission of volatile organic compounds associated with respiration, destruction of chlorophylls, synthesis of new pigments (red/yellow carotenoids plus xanthophylls and anthocyanins), formation of pectins and protein synthesis. The involvement of nitric oxide (NO) in fruit ripening has been established, but more work is needed to detail the metabolic networks involving NO and other reactive nitrogen species (RNS) in the process. It has been reported that RNS can mediate post-translational modifications of proteins, which can modulate physiological processes through mechanisms of cellular signalling. This study therefore examined the potential role of NO in nitration of tyrosine during the ripening of California sweet pepper.
  
  
  METHODS
  The NO content of green and red pepper fruit was determined spectrofluorometrically. Fruits at the breaking point between green and red coloration were incubated in the presence of NO for 1 h and then left to ripen for 3 d. Profiles of nitrated proteins were determined using an antibody against nitro-tyrosine (NO2-Tyr), and profiles of nitrosothiols were determined by confocal laser scanning microscopy. Nitrated proteins were identified by 2-D electrophoresis and MALDI-TOF/TOF analysis.
  
  
  RESULTS
  Treatment with NO delayed the ripening of fruit. An enhancement of nitrosothiols and nitroproteins was observed in fruit during ripening, and this was reversed by the addition of exogenous NO gas. Six nitrated proteins were identified and were characterized as being involved in redox, protein, carbohydrate and oxidative metabolism, and in glutamate biosynthesis. Catalase was the most abundant nitrated protein found in both green and red fruit.
  
  
  CONCLUSIONS
  The RNS profile reported here indicates that ripening of pepper fruit is characterized by an enhancement of S-nitrosothiols and protein tyrosine nitration. The nitrated proteins identified have important functions in photosynthesis, generation of NADPH, proteolysis, amino acid biosynthesis and oxidative metabolism. The decrease of catalase in red fruit implies a lower capacity to scavenge H2O2, which would promote lipid peroxidation, as has already been reported in ripe pepper fruit.
authors: Group of Antioxidants, Free Radicals and Nitric Oxide in Biotechnology, Food and Agriculture, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, CSIC, Apartado 419, 18008 Granada, Spain and.
authors: Mounira
authors: M
authors: Chaki
authors: Group of Antioxidants, Free Radicals and Nitric Oxide in Biotechnology, Food and Agriculture, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, CSIC, Apartado 419, 18008 Granada, Spain and.
authors: Paz
authors: P
authors: Álvarez de Morales
authors: Group of Antioxidants, Free Radicals and Nitric Oxide in Biotechnology, Food and Agriculture, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, CSIC, Apartado 419, 18008 Granada, Spain and.
authors: Carmelo
authors: C
authors: Ruiz
authors: Group of Biochemistry and Cell Signaling in Nitric Oxide. Department of Biochemistry and Molecular Biology, University of Jaén, 23071 Jaén, Spain.
authors: Juan C
authors: JC
authors: Begara-Morales
authors: Group of Biochemistry and Cell Signaling in Nitric Oxide. Department of Biochemistry and Molecular Biology, University of Jaén, 23071 Jaén, Spain.
authors: Juan B
authors: JB
authors: Barroso
authors: Group of Antioxidants, Free Radicals and Nitric Oxide in Biotechnology, Food and Agriculture, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, CSIC, Apartado 419, 18008 Granada, Spain and.
authors: Francisco J
authors: FJ
authors: Corpas
authors: Group of Antioxidants, Free Radicals and Nitric Oxide in Biotechnology, Food and Agriculture, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, CSIC, Apartado 419, 18008 Granada, Spain and josemanuel.palma@eez.csic.es.
authors: José M
authors: JM
authors: Palma
mesh_terms: D002212:Capsicum / Q000254:growth & development* / Q000378:metabolism; D005638:Fruit / Q000254:growth & development / Q000378:metabolism; D009574:Nitro Compounds / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D040901:Proteomics; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D009574:Nitro Compounds; D010940:Plant Proteins; D014443:Tyrosine
keywords: Capsicum annuum; MALDI-TOF/TOF; NO gas; RNS; Solanaceae; confocal laser scanning microscopy; nitric oxide; nitro-tyrosine; nitrosothiols; pepper fruit; protein nitration; proteomics; reactive nitrogen species; ripening