Article ID Journal Published Year Pages File Type
7584992 Food Chemistry 2018 34 Pages PDF
Abstract
Phenoloxidases (POs) play a crucial role in melanization of crustaceans. There are at least two types of POs characterized in crustaceans: the conventional type (POα here) that is expressed in hemocytes and POβ, a secreted protein synthesized in the hepatopancreas. We investigated the source of PO activity in the hemolymph of a lobster and determined the kinetic parameters of mono- and di-PO activities. In the lobster hemolymph, POα, which formed a hexamer similar to both POβ and hemocyanin, contributed to PO activity, whereas the amount of POβ was low. Kinetic analyses using purified prophenoloxidase of crustaceans showed that lobster POα has a higher rate constant, while shrimp POβ has higher specificity in both mono- and di-PO reactions, when tyramine and dopamine were employed as substrates. There should be at least two types of PO molecules in crustacean hemolymph, but the dominant PO molecule type varies among species.
Related Topics
Physical Sciences and Engineering Chemistry Analytical Chemistry
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