Organelle-Specific Isozymes of Citrate Synthase in the Endosperm of Developing Ricinus Seedlings

Chromatographic analysis of organelle-associated citrate synthase activity revealed distinct mitochondrial and glyoxysomal forms of the enzyme. The chromatographic elution patterns on hydroxylapatite, carboxymethylcellulose and DEAE-cellulose of citrate synthase from the endosperm of 4.5-day-old castor bean seedlings revealed significant differences for mitochondrial and glyoxysomal activities of the enzyme. The endoplasmic reticulum-associated citrate synthase activity eluted from DEAE-cellulose in a pattern that was identical to that of the glyoxysomal activity. The same kinds of organelle specific isozyme elution patterns were observed with young, developing seedlings. Gibberellic acid-treatment of young seedlings increased total recoverable citrate synthase activity from endosperm tissue but did not modify the organelle specific isozyme relationships.