3-Crustacyanin

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

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... 

UNRAVELLING THE CHEMICAL BASIS OF THE BATHOCHROMIC SHIFT OF THE LOBSTER CARAPACE CAROTENOPROTEIN CRUSTACYANIN... 

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)... 

The bathochromic shift in biology, as exemplified by the lobster crustacyanin case, is an amazing example of interactions of various molecules and of the relevance of atomic electron states as manipulated by those interactions. 

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... 

Structure 44, Fig. 19, was recently proposed for protonated astaxanthin in crustacyanin with the delocalisation of the positive charge on the polyene chain mainly close to the rings [9]. Acidic amino acids were at that time suggested to be responsible for the protonation of the carotenoid. 

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. ... 

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