The Conversion of C14O2 and CH3-C14O-COOH to Citric and Malic Acids in the Tomato Fruits

Abstract

Mature green tomatoes were treated with C14O2 and pyruvate-2-Cl4 in separate experiments. Major portion of the incorporated activity was detected in the fruit acids and amino acids fractions. Degradation studies on malic and citric acids isolated from the fruit used in these experiments indicated that: (1) CO2 fixation is operative in this fruit; (2) CO2 fixation appeared not to be the major pathway for malic acid biosynthesis in the dark; and (3) small amount of CO2 is incorporated directly into the tertiary carboxyl-C atom of citric acid probably by way of isocitrate formation from alpha-ketoglutarate and CO2.