INVESTIGATION OF CHROMOPEPTIDES FROM C‐PHYCOCYANIN BY UV‐VIS ABSORPTION, EMISSION AND CIRCULAR DICHROISM SPECTROSCOPY

Four different chromopeptides were isolated after digestion of C-phycocyanin with pepsin. Their UV-vis absorption and circular dichroism spectra were measured at two different pH values without and with urea present in the buffered solutions. For one chromopeptide, fluorescence spectra and the kinetics of fluorescence decay were studied in more detail. The results are discussed in comparison with quantum-mechanical model calculations. It is concluded that due to the interaction between the oligopeptide chain and the chromophore, the latter is present as a mixture of helical and semi-extended forms, respectively.