Oxidation of proline and pyruvate by flight muscle mitochondria of the Colorado beetle, Leptinotarsa decemlineata Say

Abstract Mitochondria isolated from the flight muscles of the Colorado beetle Leptinotarsa decemlineata show high rates of respiration for proline and pyruvate. The rate of oxidation of Krebs cycle intermediates is comparatively low. The amount of alanine formed during in vitro oxidation of proline is equal to the amount of proline used. The results suggest that proline oxidation leads to pyruvate formation and subsequent alanine synthesis. The specific activity of NAD-dependent malic enzyme is high and is supposed to participate in pyruvate formation. In the presence of low proline concentrations, pyruvate and proline oxidations are fully additive. At proline concentrations above 1 mM both oxidations do not seem to occur simultaneously.