Phenoloxidase from the Cuticle of Florida Spiny Lobster (Panulirus argus): Mode of Activation and Characterization

Abstract

Phcnoloxidase(PO) from lobster cuticle existed as a large inert enzyme (IPOI) which became active (15fold increase) upon incubation at 4°C and 3 days storage. Electrophoresis of day 3 extracts showed that the large enzyme disappeared gradually while a new PO (EAPO) developed (Mw of 62.5 kDA).

Properties of polyphenol oxidase in mango (Mangifera indica) kernel

“…Calculated and values for K m V max mango kernel PPO using catechol as substrate were 24É6 mM and 2É14 units g~1 kernel, respectively. Michaelis constants of 9É67 mM (substrate, catechol) for Concord grape PPO (Ferrer et al 1989) and 40 mM and 8É7 mM (substrate, ( ] )catechin) for two di †erent isozymes of kiwifruit PPO (Park and Luh 1985) have been reported. Chickpea seeds had relative PPO activities (units g~1 seed) of \1^0É1 (substrate, catechol), 2^0É1 (substrate, gallic acid) and 1^0É1 (substrate, pyrogallol).…”

“…Manometric, polarographic, chromometric and spectrophotometric methods are available for the assay of PPO (Whitaker 1972). PPO activity has been reported on potatoes (Patil and Zucker 1965), wheat grains (Kruger 1976), table beets (Lee and Smith 1979), avocadoes (Sharon-Raber and Kahn 1983), kiwifruits (Park and Luh 1985), legume seeds (Udayasekhara Rao and Deosthale 1987), lobsters (Ferrer et al 1989), mushrooms (Fasidi and Kadiri 1991), and tea leaves (Singh and Ravindranath 1994).…”

Effect of catechin and its derivatives on inhibition of polyphenoloxidase and melanosis of Pacific white shrimp

“…Additionally, the mechanism of melanosis inhibition by SMS and EGCG might be different. SMS inhibits melanosis by reacting with intermediate quinone, forming sulfoquinone or it can act as a competitive inhibitor (Ferrer et al 1989). During 8-10 days of storage, the lowest melanosis score was observed in the sample treated with 0.5 or 0.75% EGCG, followed by those treated with SMS and 0.25% EGCG, respectively.…”

Melanosis inhibition and SO2 residual levels in shrimps (Parapenaeus longirostris) after different sulfite‐based treatments

“…3 Bisulfite appears to inhibit melanosis by two mechanisms: (1) reacting with intermediate quinones in the melanosis reaction, forming sulfoquinones, and (2) irreversibly reacting with PPO, causing complete inactivation. 4 A common practice is to use commercial products containing another substance(s), in addition to sodium metabisulfite, which contribute to retard melanosis. Some of these are reducing agents, which act by causing chemical reduction of the pigment precursors (ascorbic acid, ascorbyl derivatives), acidulants (citric acid, phosphoric acid) or chelating agents to reduce the level of copper available (ethylenediaminetretracetic acid) (EDTA).…”