ENZYME-ENZYME INTERACTION IN THE CHLOROPLAST - GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE, TRIOSE PHOSPHATE ISOMERASE AND ALDOLASE

Apparent physical interaction between pea chloroplast (Pisum sativum L .) glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13) and aldolase (EC 4.1.2.13) is seen in phase-partitioning, fluorescent-anisotropy a nd isoelectric-focusing experiments. Similarly, results obtained in ph ase-partitioning and isoelectric-focusing experiments indicate physica l interaction between aldolase and triose-phosphate isomerase (EC 5.3. 1.1). Kinetic experiments suggest that both aldolase-bound glyceraldeh yde-3-phosphate and triose-phosphate isomerase-bound glyceraldehyde-3- phosphate can act as substrate for glyceraldehyde-3-phosphate dehydrog enase. These results are consistent with the notion that there is inte raction between these three enzymes both during photosynthetic CO2 fix ation and during glycolysis in the chloroplast.