UV-VIS Absorption Spectra at High Pressure of C-Phycocyanin and Allophycocyanin from Mastigocladus laminosus

The behaviour o f monomers and trimers o f C-phycocyanin and allophycocyanin under high pressure is studied by UV-VIS absorption spectroscopy. It is found that fast variations o f pres­ sure (Ap > 500 bar) and/or temperature are accompanied by significant changes in the absorp­ tion spectra (intensity and/or spectral shift). The induced differences disappear, however, in part, when the samples are left for several minutes at the final pressure (relaxation effect). The observed spectral variations are different from those connected with a change in state o f aggre­ gation and could therefore be due to small modifications o f the chromophore-protein arrange­ ment.