title: Protein-chromophore interactions in alpha-crustacyanin, the major blue carotenoprotein from the carapace of the lobster, Homarus gammarus. A study by 13C magic angle spinning NMR.
abstract: MAS (magic angle spinning) 13C NMR has been used to study protein-chromophore interactions in alpha-crustacyanin, the blue astaxanthin-binding carotenoprotein of the lobster, Homarus gammarus, reconstituted with astaxanthins labelled with 13C at the 14,14' or 15,15' positions. Two signals are seen for alpha-crustacyanin containing [14,14'-13C2]astaxanthin, shifted 6.9 and 4.0 ppm downfield from the 134.1 ppm signal of uncomplexed astaxanthin in the solid state. With alpha-crustacyanin containing [15,15'-13C2]astaxanthin, one essentially unshifted broad signal is seen. Hence binding to the protein causes a decrease in electronic charge density, providing the first experimental evidence that a charge redistribution mechanism contributes to the bathochromic shift of the astaxanthin in alpha-crustacyanin, in agreement with inferences based on resonance Raman data [Salares, et al. (1979) Biochim. Biophys. Acta 576, 176-191]. The splitting of the 14 and 14' signals provides evidence for asymmetric binding of each astaxanthin molecule by the protein.
authors.affiliation: Department of Biochemistry, University of Liverpool, UK.
authors.forename: R J
authors.initials: RJ
authors.lastname: Weesie
authors.forename: D
authors.initials: D
authors.lastname: Askin
authors.forename: F J
authors.initials: FJ
authors.lastname: Jansen
authors.forename: H J
authors.initials: HJ
authors.lastname: de Groot
authors.forename: J
authors.initials: J
authors.lastname: Lugtenburg
authors.forename: G
authors.initials: G
authors.lastname: Britton
mesh_terms: D000818:Animals; D002338:Carotenoids / Q000737:chemistry*; D002352:Carrier Proteins; D009682:Magnetic Resonance Spectroscopy; D008121:Nephropidae / Q000737:chemistry; D010860:Pigments, Biological / Q000737:chemistry*; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D024341:Xanthophylls; D019207:beta Carotene / Q000031:analogs & derivatives*
chemical_list: D002352:Carrier Proteins; D010860:Pigments, Biological; D011506:Proteins; D024341:Xanthophylls; C018494:crustacyanins; D019207:beta Carotene; D002338:Carotenoids; C005948:astaxanthine