Presence of hemocyanin with diphenoloxidase activity in deepwater pink shrimp (Parapenaeus longirostris) post mortem

Abstract

Polyphenoloxidase and hemocyanin are two proteins which although very similar perform different physiological functions in crustaceans. This paper reports the presence of 15 hemocyanin with diphenoloxidase activity in deepwater pink shrimp (Parapenaeus longirostris) post mortem. Polyacrylamide gels and specific inhibitors and substrates of 17 mono-and diphenoloxidases were used for purposes of recognition, and MALDI-TOF mass 18 spectrometry for identification. Presumptive polyphenoloxidase was found in an inactive 19 form in cephalothorax following capture, subsequently becoming active during storage. Also 20 in the course of storage, hemocyanin acquired the ability to oxidize diphenols. Ascorbic acid, 21 sodium metabisulphite and tropolone inhibited the prooxidant activity of both presumptive polyphenoloxidase and hemocyanin in the gels. 4-hexylresorcinol did not avoid the appearance of activity bands in the gel corresponding with hemocyanin, maybe because 4hexylresorcinol is described as slow-binding inhibitor. The acquired prooxidant activity of hemocyanin following capture is especially important because of the rapid development of melanosis in deepwater pink shrimp during storage.

Reconsideration of phenoloxidase activity determination in white shrimp Litopenaeus vannamei

“…These results suggest that the samples are quite unstable with spontaneous activation when put on ice. This so-called ''spontaneous activation'' is probably not related to the immunity of the organism any more, but related to the melanization reaction caused by hemocyanins of shrimp post-mortem [24]. Thus, the samples need to be preserved or measured immediately, and the preserved samples should be assayed as soon as possible after it is thawed.…”

The effect of several cooking treatments on subsequent chilled storage of thawed deepwater pink shrimp (Parapenaeus longirostris) treated with different melanosis-inhibiting formulas

“…These results coincide with those reported by Niamnuy et al (2007), which described the appearance of black spots in white shrimp boiled for 3 min. According to Williams et al (2003), prolonged exposure to moderate temperatures (50-60 C) could increase total PPO activity, possibly due to the impact of heat on hemocyanin, which shows intense oxidative activity in pink shrimp (Martínez-Alvarez, Gó mez-Guillé n, & Montero, 2008). This might result in a build up of quinones during cooking, which could polymerize during storage and cause melanosis.…”

Characterization of phenoloxidase activity of carapace and viscera from cephalothorax of Norway lobster (Nephrops norvegicus)

“…3, lane 6). In crustaceans, the presence of hemocyanin with acquired phenoloxidase activity has been reported by different authors (Decker & Jaenicke, 2004;García-Carreño et al, 2008;Martínez-Alvarez et al, 2008a). However, converted-hemocyanin into PPOlike enzyme has been mostly described as o-diphenoloxidase.…”

“…However, the active site for PPO and hemocyanin is quite similar (Ling et al, 1994). Increasing evidences for a potential contribution of hemocyanin to the PPO activity have been reported in some crustacean species (Adachi, Hirata, Fujio, Nishioka, & Sakaguchi, 2003a;García-Carreño, Cota, & Navarrete del Toro, 2008;Martínez-Alvarez, Gómez-Guillén, & Montero, 2008a). Hemocyanin could be converted into the PPO enzyme by a yet unknown mechanism, though limited proteolysis, changes in pH and conformational changes induced by some hemolymphs factors have been hypothesised as activating processes (Adachi, Hirata, Nagai, & Sakaguchi, 2001;Decker & Jaenicke, 2004).…”