Blue crustacyanin

Conjugated keto-carotenoids are complexed stoichiometrically with a simple protein in true carotenoproteins. Such carotenoproteins are encountered particularly in external tissues in the carapace of Crustacea and the skin of Echinodermata. The blue crustacyanin from lobster carapace is the best studied carotenoprotein, as described in several reviews [8,81,82], Detailed isolations methods are given [83], Our group has been involved in early studies on crustacyanin [84], asteriarubin [85], alloporin [86] and linckia-cyanin [87]. 

Absorption spectra of astaxanthin (red line) in methanol and astaxanthin bound in crustacyanin protein (blue line). 

Astaxanthin (17) is not covalently bound in carotenoproteins and may be extracted from crustacyanin, providing a colourless apoprotein. The blue colour may be reconstituted with a range of conjugated ketocarotenoids [88], All optical isomers (3i ,3 i 3S,3 S and the meso... 

Consequently, the current picture concerning the bathochromic shift in carotenoproteins, such a crustacyanin (9), involves partial positive charge caused by hydrogen bonding of the astaxanthin (17) keto groups, cf. the blue oxonium ions discussed above. 

Milicua JCG, Garate AM, Barbon PG, Gomez R (1986) Relatedness between a-crustacyanin from the lobster Homarus americanus and the blue carotenoprotein from the crayfish Procambrus clarkii. Comp Biochem Physiol 85B 621-626... 

Astaxanthin is present in crab and lobster shells and lobsters, the red astaxanthin is released from and, in combination with proteins, provides three a green carotenoid-protein complex. Astaxanthin blue hues (a-, 3- and y-crustacyanin) and one usually occurs in lobster shell as an ester, e. g., diyellow pigment. During the cooking of crabs palmitic ester. 

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