Different peptidase activities do not contribute to tomate pool of ripe tomato fruits

SORREQUIETA, A.; SILVANA BEATRIZ BOGGIO; VALLE, E. M.

Rosario

Congreso; XLII Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2006

SAIB

DIFFERENT PEPTIDASE ACTIVITIES CONTRIBUTE TO GLUTAMATE POOL OF RIPE TOMATO FRUIT. Sorrequieta, Augusto; Boggio, Silvana B.; Valle Estela M. Inst. de Bio. Molec. y Cel. de Rosario (IBR)CONICET-UNR, , Suipacha 531, S2002LRK Rosario. E-mail: sorrequieta@ibr.gov.ar Glutamate is the most abundant free amino acid of ripe fruit of several Solanum lycopersicum, particularly in those cultivars producing palatable small fruits. The glutamate sources in non-photosynthetic organs such us ripe fruit are  still a matter of discussion. Among them, we explored the in-situ enzymatic production of glutamate in the pericarp of mature fruit during the ripening transition. A marked increase in (-glutamyl transpeptidase activity was observed, which contributed to liberate glutamate at a …..rate per g fresh fruit. Different endopeptidases are present in mature fruit, being the substrate specificity characteristic of each ripening phase. Azocasein was the preferred substrate for ripe fruit, while endogenous proteins were for green fruit. Glutamate residues from added exogenous polypeptides were also degraded in ripe fruit, as well as an endogenous high molecular weight molecule that is present mainly in green fruit. All these results indicate that several trans-, endo- and exopeptidases are present in ripe pericarp fruit, which could contribute to increase the glutamate content of tomato fruit during the ripening transition. The regulation of these activities is currently under study.     Inst. de Bio. Molec. y Cel. de Rosario (IBR)CONICET-UNR, , Suipacha 531, S2002LRK Rosario