Involved in the metabolic adaptation in response to environmental changes. Catalyzes the reversible formation of succinate and glyoxylate from isocitrate, a key step of the glyoxylate cycle, which operates as an anaplerotic route for replenishing the tricarboxylic acid cycle during growth on fatty acid substrates. D-threo-isocitrate = glyoxylate + succinate Optimum pH is 7. Very little activity is detected at pH 6.1 or 8.0. Optimum temperature is 55 degrees Celsius. Very little activity is found above 65 degrees Celsius, and the activity at 40 degrees Celsius is 50% of the maximum. Carbohydrate metabolism; glyoxylate cycle; (S)-malate from isocitrate: step 1/2. Homotetramer or homotrimer. Belongs to the isocitrate lyase/PEP mutase superfamily.