CRYOPROTECTANT-INDUCED QUENCHING OF CHLOROPHYLL-A FLUORESCENCE FROM LIGHT-HARVESTING COMPLEX-2 IN-VITRO - TIME-RESOLVED FLUORESCENCE AND STEADY-STATE SPECTROSCOPIC STUDIES

Polyalcohols introduced efficient dissipative channels leading to a de crease of the average fluorescence lifetime from 4.3 to 1.0-0.6 ns, an d the appearance of long-wavelength forms in the Iow-temperature fluor escence emission spectra, owing to the formation of aggregates. Aggreg ated light-harvesting chlorophyll-protein complex 2 (LHC2) suitable fo r the low-temperature absorption spectroscopy was obtained by incubati on of a solubilized sample with ethylene glycol. Only a minor differen ce (red shift of about I nm which can be attributed to changes of the trimer conformation due to the aggregation) was observed between the a bsorption spectra of aggregated and solubilized LHC2 at 4 K. Thus, no indications were found for the formation of new long-wavelength chloro phyll forms in this type of aggregated LHC2.