The glyoxylate cycle in Polytomella caeca

• 1.1. The two enzymes unique to the glyoxylate cycle, isocitrate lyase and malate synthase, have been shown to be present in Polytomella caeca.
• 2.2. Malate synthase is virtually confined to the particulate fraction. Isocitrate lyase is predominantly cytoplasmic, but is present in small amounts in the particles.
• 3.3. Tracer experiments showed malate to be the most highly labeled compound at short times after feeding acetate-2-C¹⁴. Radioactivity in malate, as a percentage of the total incorporated, was at its maximum before succinate reached its maximum, thus suggesting that malate did not arise primarily from succinate and therefore supporting the suggestion that the glyoxylate cycle was operating. An unexpectedly low level of labeling occurred in citric acid.