Mj. Lee et Jh. Anstee, PHENOLOXIDASE AND ITS ZYMOGEN FROM THE HEMOLYMPH OF LARVAE OF THE LEPIDOPTERAN SPODOPTERA-LITTORALIS (LEPIDOPTERA, NOCTUIDAE), Comparative biochemistry and physiology. B. Comparative biochemistry, 110(2), 1995, pp. 379-384
Haemolymph serum phenoloxidase from larvae of the noctuid moth Spodopt
era littoralis is present as an inactive proenzyme, prophenoloxidase.
Partially purified serum prophenoloxidase was activated by methanol, b
ut not by laminarin, lipopolysaccharides, bovine trypsin or chymotryps
in. Phenoloxidase activity was optimal between pH 7.0 and 7.5 for the
oxidation of L-DOPA, with an apparent K-m of 1.35 mM for this substrat
e. Both Mg2+ and Ca2+ stimulated phenoloxidase activity compared with
controls and maximal stimulation was observed at about 30 mM for both
ions. EDTA had little effect on activity even at high concentrations.
Phenoloxidase activity was inhibited by dithiothreitol (50% inhibition
at 20 mu M) and kojic acid (50% inhibition at 135 mu M, inhibition co
nstant of 69 mu M).