PARENT SESSION
Posters P4Aa Chlorophyll and bilin based antenna systems. Abstracts (239-271)

Fluorescence quenching in LHCII is caused by structural variations. Bart van Oort¹, Alexander Ruban², Arie van Hoek¹, Herbert van Amerongen^*,1, ¹ Wageningen University, Wageningen, The Netherlands² University of Sheffield, Sheffield, UK

ABSTRACT- We have performed fluorescence lifetime measurements on LHCII in different forms of oligomerization/aggregation. Only in the case of trimeric LHCII we observe fluorescence decay behavior, which is essentially mono-exponential and hardly any quenching is observed. However, both monomers and small oligomers show multi-exponential fluorescence behavior and fluorescence quenching is present. Upon lowering the detergent concentration below the CMC, monomers, trimers and oligomers start to aggregate and show extremely multi-exponential behavior and substantial fluorescence quenching. In principle one might explain an increase of quenching upon aggregation by assuming that a small amount of quenchers in the original non-aggregated preparation is able to quench many excitations in the aggregated samples due to efficient energy transfer throughout the aggregates. However, we demonstrate that this is not the case and that the quenchers are being created upon aggregation.

KEY WORDS: light harvesting, nonphotochemical quenching, time-resolved fluorescence, photosystem II