title: Hemocyanin-derived phenoloxidase activity: a contributing factor to hyperpigmentation in Nephrops norvegicus.
abstract: The phenomenon of hyperpigmentation (melanosis) in shellfish has long been attributed to phenoloxidase enzymes. Over the last number of years, the oxygen carrier hemocyanin, has demonstrated several immune- and physiological functionalities, most notably, inducible phenoloxidase activity. In this study, hemocyanin purified from the hemolymph of Nephrops norvegicus displays diphenoloxidase activity in the presence of a number of elicitors and retains structural and functional integrity throughout the process of freeze-thawing (at -25 °C). Conversely, cellular phenoloxidase activity (present in cell-lysates), demonstrates >98% reduction in activity after freeze-thawing. We present evidence that hemocyanin may act as a causative agent of hyperpigmentation in N. norvegicus. The inhibition of hemocyanin-derived phenoloxidase activity is discussed, and for the first time, the biophysical interactions of shellfish hemocyanin with known phenoloxidase inhibitors are presented.
authors.affiliation: Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, Scotland, UK. c.j.coates@stir.ac.uk
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Coates
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Nairn
mesh_terms: D000818:Animals; D004795:Enzyme Stability; D006433:Hemocyanins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006458:Hemolymph / Q000737:chemistry / Q000201:enzymology; D007700:Kinetics; D014442:Monophenol Monooxygenase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008121:Nephropidae / Q000737:chemistry / Q000201:enzymology*; D010858:Pigmentation
chemical_list: D006433:Hemocyanins; D014442:Monophenol Monooxygenase