Prophenoloxidase from brown shrimp (Penaeus californiensis) hemocytes

Purification and characterisation of phenoloxidase from amphioxus Branchiostoma belcheri tsingtauense

“…This is similar to the enzymes from the haemocytes of Penaeus californiensis and Pacifastacus leniusculus, and from the egg masses of Biomphalaria glabrata [22,47,49]. Fig.…”

“…The purified enzyme exhibited a single band of 150 kDa under non-reducing conditions, and was resolved to three bands with molecular masses of 72, 46 and 44 kDa, respectively, under reducing conditions, that were all cross-reactive with mouse anti-PO sera. It has been shown that PO and proPO generally exist as a homodimer [23,47] or heterodimer [28,48]. However, our results here suggest that the PO in amphioxus humoral fluid seems to be a heterotrimer of three polypeptides held together by disulphide bonds.…”

Properties of phenoloxidase from haemocytes of Scylla tranquebarica

“…In general, the enzyme-catalysed reactions proceed via the formation of enzyme substrate complex in which substrates bounds non-covalently to the active site of the enzyme [15] and the use of L-dopa as substrate in detecting the PO activity was reported in many crustaceans. The Km value for L-dopa in PO activity of this crab was found to be much close to the reports from Penaeus californiensis [7]. Moreover, PO of crustaceans has higher activity with diphenols and the result of the present study is comparable to the above reports from various invertebrates.…”

“…Moreover, PO of crustaceans has higher activity with diphenols and the result of the present study is comparable to the above reports from various invertebrates. The optimum pH for PO activity is 8.0 in S. tranquebarica, which was similar to brown shrimp, P. californiensis [7]. pH forms an important factor for the enzyme action because the ionization of aminoacid residues in the active site of an enzyme depends on the optimum pH [13].…”

“…The location of proPO is highly varied among arthropods. However, in decapod crustaceans, proPO is located mainly in granular haemocytes and haemocyte lysate supernatant was used as the enzyme source [5][6][7][8]. Although, the presence of a proPO system involved in non-self recognition is well documented in decapods, no such reports are available for Scylla tranquebarica.…”