A-crustacyanin

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. 

Carotenoid-Protein Complexes. The partial characterization of an astaxanthin- or zeaxanthin-containing carotenoprotein (mol. wt. >30000) from hydrocorals has been reported. Other papers present a spectroscopic characterization of the lobster pigment a-crustacyanin and report effects of changes in pH and ionic strength on its spectroscopic properties. ... 

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... 

Lately the CD spectrum of the carotenoprotein a-crustacyanin which exhibits two maxima at 690 nm (-b) and 583 nm (—), in phosphate buffer has been interpreted in terms of dipole-dipole coupling between the transition moments of the two carotenoid molecules on each subunit. The CD splitting corresponded to an exciton band width of 2800 cm which leads to an interchromophore distance of ca. 13 A 123 a). 

P. F. Zagalsky, E. E. Eliopoulos, and J. B. Findlay, The lobster carapace carotenoprotein, alpha-crustacyanin. A possible role for tryptophan in the bathchromic spectral shift of protein-bound astaxanthin, J. Biochem. 274 (1991) 79-83. 

In an endeavor to explain the anomolous spectral shifts when certain carotenoids such as astaxanthin and all-trans retinal are incorporated into their respective apoproteins, crustacyanin, and opsin, the perturbation of the absorption spectra of the chromophores adsorbed onto silica gel has been examined.37,38 Buckwald and Jencks 37 found that there was a small red shift... 

Infrared and Resonance Raman Spectroscopy. Reviewson the uses of resonance Raman spectroscopy in biochemistry and biology include sections on carotenoproteins, visual pigments, and bacteriorhodopsin. The resonance Raman spectrum of the lowest excited triplet state of /3-carotene has been reported.A resonance Raman method has been used for the quantitative analysis of /3-carotene and lutein (20) in tobacco.The mechanism of carotenoid-protein interactions in the carotenoproteins ovoverdin and /3-crustacyanin has been investigated by resonance Raman spectroscopy. " 2 axanthin (24) has been used as a resonance Raman probe of membrane structure. " The resonance Raman spectra have been reported of all-frans-anhydrovitamin A (194), " /3-ionone, retinals, and Schiff bases.The technique has been used extensively to study... 

Figure 8-3. (a) ASX in hexane at a dilution similar to that in lobster crustacyanin (left) (b) beta-crustacyanin (right). From Dr P Zagalsky with permission (see color plate section)... 

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]. 

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... 

In p-crustacyanin, several amino acids of the apoproteins form hydrogen bonds to two molecules of astaxanthin (Fig. 7.25). [39, 43] The two astaxan-thin molecules are at a distance of 7 A and constitute an exciton coupling system. Further, and perhaps more significant contributions to the enormous bathochromic shift are due to the elongation of the n-system, caused by the coplanarity of the cyclic end groups and by partial polarisation of the keto-groups. 

The molecular topology of the peridinin (30)-chlorophyll-protein complex (122) and of crustacyanin (123 a) has recently been studied and future progress in this field is anticipated. 

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. 

After being ingested, astaxanthin molecules are assembled in a large protein called crustacyanin and then bound in the calcified outer... 

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