Some purple bacteria species, such as Rhodopseudomonas palustris 2.1.6, produce light harvesting antenna (LH2) with unusual absorption spectra when they are grown under low-light intensities. This ability is often related to the presence of multiple genes encoding the LH2 apoproteins. This thesis describes isolation of pure stable LH2s from Rhodopseudomonas palustris 2.1.6 grown at different light intensities, determination of the polypeptide composition of high- (HL) and low-light (LL) LH2 complexes and characterisation their spectroscopic properties using various optical spectroscopies. The question of whether rings with a heterogeneous apoprotein composition exist has been addressed by single-molecule spectroscopy. For the first time, direct evidence that individual LL LH2 complexes have a heterogeneous αβ-apoprotein composition has been found. Such mixed rings feature Bchl a molecules with both B820-like and B850-like site-energies. This finding was supported by a femtosecond study on the energy transfer reactions and exciton relaxations within both HL and LL LH2 complexes. This thesis also describes attempts to crystallise the HL and LL LH2s. Even though three-dimensional crystals of both HL and LL LH2 complexes only diffracted to low resolution, it was possible to use molecular replacement to obtain structures that suggest both these types of LH2s are nonamers.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:513212 |
| Date | January 2009 |
| Creators | Brotosudarmo, Tatas Hardo Panintingjati |
| Publisher | University of Glasgow |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://theses.gla.ac.uk/1619/ |
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