Hemocyanin-derived phenoloxidase activity: A contributing factor to hyperpigmentation in Nephrops norvegicus

Citation

Coates C & Nairn J (2013) Hemocyanin-derived phenoloxidase activity: A contributing factor to hyperpigmentation in Nephrops norvegicus. Food Chemistry, 140 (1-2), pp. 361-369. https://doi.org/10.1016/j.foodchem.2013.02.072

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.

Keywords
Hemocyanin; Phenoloxidase; Hyperpigmentation; Innate immunity; Enzyme inhibition; Invertebrates

Journal
Food Chemistry: Volume 140, Issue 1-2