Effect of Pressure on the Absorption Spectra of Phycobiliprotein and Porphyridium cruentum

Changes in the absorption spectra o f P. cruentum and phycobiliprotein are observed as a function o f hydrostatic pressure. With phycobiliprotein both in solution and in algae, increasing hydrostatic pressure results in bathochromic shifts o f the absorption maxima. In addition, there is a splitting o f the absorption band of phycoerythrin. When P. cruentum is subjected to 250 bars there are increases in absorption by chlorophyll (at 700 and 698 nm), phycocyanin (at 640 nm) and phycoerythrin (at 580 and 550 nm). When a cell free solution of phycobiliprotein is subjected to 300 bars there are increases in absorption by phycoerythrin (at 570 and 550 nm) and phycocyanin (at 634 nm).