THE INTERACTIONS BETWEEN BACTERIOCHLOROPHYLL-C AND AMPHIPHILIC PEPTIDES

Absorption, fluorescence, photoacoustic and delayed luminescence spect ra of bacteriochlorophyll c with and without peptides located in dimet hyl sulfoxide were measured. For most molecules, the hydrophobic inter actions between peptide and pigment in the ground state seems not to b e very strong, as it follows from the absorption spectra of the sample s with and without peptides. From photoacoustic spectra, it seems that at least part of the illuminated pigment molecules are forming comple xes with peptides. These complexes are very efficient in thermal deact ivation of excitation. The occurrence of the interactions between pept ides and bacteriochlorophyll c follows also from delayed luminescence spectra, which are different for the sample with and without peptides. The observed delayed luminescence is so-called delayed fluorescence o r E-type delayed luminescence because it is generated by thermal activ ation from the triplet to first excited state followed by emission fro m this state. (C) 1998 Elsevier Science S.A. All rights reserved.