Hi

One of these may have what you need.

Bill

58. Studies on spectral characteristics of allophycocyanin isolated from Anabaena cylindrica: curve-fitting analysis

By Mimuro, Mamoru; Murakami, Akio; Fujita, Yoshihiko

From Archives of Biochemistry and Biophysics (1982), 215(1), 266-73. DOI:10.1016/0003-9861(82)90304-6

Spectroscopic characteristics of allophycocyanin (APC) isolated from A. cylindrica were studied by curve-fitting analyses of absorption spectra measured at room temp. Gaussian curve-fittings based on the least-squares method were done on absorption spectra for 3 different dissocn.-assocn. conditions of the protein. The compn. of the component bands was similar in the 3 absorption spectra and could be classified into 3 groups depending on changes in band intensity; the 1st group was represented by the main band at 653 nm, which was intense in the trimer APC but markedly reduced in the monomer. The 2nd group was represented by the main band at 607 nm, which showed opposite changes. The 3rd group had its main band at 623 nm, and it remained the same in the 3 absorption spectra. The sum of the band area of the variable components was almost equal to that of the const. components. Thus, APC has 2 types of phycocyanobilin (PCB), which differ in their spectroscopic characteristics. The PCB responsible for the variable component bands, and thus for the spectral changes, has 2 excitation states corresponding to 653 and 607 nm, and the spectral changes are ascribable to variations in the relative frequencies of occurrence of the 2 states: in assocd. APC the 1st state predominates, and in dissocd. APC, the 2nd. PCB for the const. component bands has only 1 excitation state, corresponding to the 623-nm band. Changes in the emission spectra correlate with these changes in the absorption spectra, suggesting that in APC the PCB species responsible for and independent of absorption spectrum changes act as the fluorescing and sensitizing types, resp.

60. Structure and properties of phycocyanobilin and related bilatrienes

By Cole, W. J.; Chapman, D. J.; Siegelman, H. W.

From Biochemistry (1968), 7(8), 2929-35. DOI:10.1021/bi00848a033

Phycocyanobilin, the chromophore of the biliprotein C-phycocyanin, was isolated from Cl3CCO2H-denatured protein by boiling under reflux in MeOH. The algal pigment was purified and crystallized as the dimethyl ester, and its uv visible absorption spectra were compared with those of known bilatriene pigments. Alk. KMnO4 oxidn. of phycocyanobilin revealed that the 2 central pyrrole rings contained the same β substituents as the IXα bile pigments. The dimethyl esters of phycocyanobilin (mol. wt. 614), mesobiliverdin (mol. wt. 614), and biliverdin (mol. wt. 610) had similar mass spectral fragmentation patterns. The structural differences between phycocyanobilin and mesobiliverdin were proven and confirmed by N.M.R. comparisons and decoupling expts. The facile isomerization of phycocyanobilin in alk. media to a product identical with mesobiliverdin, validated the structure proposed for phycocyanobilin. Within exptl. error the optical activity of phycocyanobilin isolated from several sources was identical, [α]DCHCL3 + 660°. It is proposed that regardless of the source, phycocyanobilin probably has the same structure and stereochem. configuration. There is a marked difference between the O.R.D. of phycocyanobilin and that of phycocyanin.

61. Comparative biochemical studies of the phycobilins

By O hEocha, Colm

From Archives of Biochemistry and Biophysics (1958), 73, 207-19.

cf. C.A. 51, 3757d. The phycobilin chromophores of representative phycocyanins and phycoerythrins were examd. after cleavage from the protein with concd. HCl at room temp. for 20-30 min. Both phycocyanobilin from C-phycocyanin and its red-fluorescing Zn complex absorbed maximally at 630 mμ in CHCl3. When acid hydrolysis was conducted for a longer period or at elevated temps., phycocyanobilin was converted to mesobiliviolin. The chromophore of allophycocyanin differed in some spectral properties from C-phycocyanobilin. A no. of spectrally different phycoerythrins all yielded the same CHCl3-sol. labile phycoerythrobilin. This bile-type pigment of unknown constitution absorbed maximally at 576 mμ in acid CHCl3 and at 583 mμ as an orange-red-fluorescing Zn complex in CHCl3.

63. A polarity probe for monitoring light-induced structural changes at the entrance of the chromophore pocket in a bacterial phytochrome

By Borucki Berthold; Lamparter Tilman

From The Journal of biological chemistry (2009), 284(38), 26005-16, Light-induced structural changes at the entrance of the chromophore pocket of Agp1 phytochrome were investigated by using a thiol-reactive fluorescein derivative that is covalently attached to the genuine chromophore binding site (Cys-20) and serves as a polarity probe. In the apoprotein, the absorption spectrum of bound fluorescein is red-shifted with respect to that of the free label suggesting that the probe enters the hydrophobic chromophore pocket. Assembly of this construct with the chromophores phycocyanobilin or biliverdin is associated with a blue-shift of the fluorescein absorption band indicating the displacement of the probe out of the pocket. The probe does not affect the photochromic and kinetic properties of the noncovalent bilin adducts. Upon photoconversion to Pfr, the probe spectrum undergoes again a bathochromic shift and a strong rise in CD indicating a more hydrophobic and asymmetric environment. We propose that the environmental changes of the probe reflect conformational changes at the entrance of the chromophore pocket and are indicative for rearrangements of the chromophore ring A. Flash photolysis measurements showed that the absorption changes of the probe are kinetically coupled to the formation of Meta-R(C) and Pfr. In the biliverdin adduct, an additional component occurs that probably reflects a transition between two Meta-RC substates. Analogous results to that of the noncovalent phycocyanobilin adduct were obtained with the mutant V249C in which probe and chromophore are covalently attached. The conformational changes of the chromophore are correlated to proton transfer to the protein surface.

72. Exciton interaction in allophycocyanin

By Csatorday K; MacColl R; Csizmadia V; Grabowski J; Bagyinka C

From Biochemistry (1984), 23(26), 6466-70, The absorption and circular dichroism (CD) spectra of allophycocyanin II in the trimer and monomer (dissociated) forms were resolved into four and two components, respectively. The short-wavelength region of the visible spectra was approximated by a chimera of Lorentzian- and Gaussian-shaped bands having a bandwidth of ca. 65 nm. The rest of the bands have a pure Gaussian form. The characteristic 652-nm band in the absorption spectrum (656 nm in the CD spectrum) is shown to arise from exciton interaction between two fluorescent phycocyanobilin chromophores.

It is fluorescent, but can be made more or less fluorescent depending on the protein it binds to. Here is a link to the absorbance spectrum and other info: http://www.rsc.org/suppdata/cc/b8/b821687h/b821687h.pdf Hopefully after 3 years this helps someone :-)