Isolation and Identification of Ripening-Related Tomato Fruit Carboxypeptidase

Tomato (Lycopersicon esculentum) fruit carboxypeptidase active on N-carbobenzoxy Z-L-phenylalanine-L-alanine was found to constitute a family of isoforms whose abundance changed differentially during ripening. A specific polyclonal antibody against the fruit carboxypeptidase was raised in rabbits and used to purify and identify the protein. The data from immunoaffinity chromatography, immunoinhibition studies, immunoprecipitation of the in vivo- and in vitro-labeled proteins, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of native isoforms strongly suggest that the fruit carboxypeptidases are monomers or oligomers of 68- and/or 43-kD subunits.