Vrije Universiteit Amsterdam, 2020

Thylakoids: from molecular to membrane organisation. A spectroscopic and nanoscopic study of the photosynthetic apparatus.

Simona Streckaite

Full thesis


Photosynthesis is one of the most important processes in the World – it provides a large part of food and energy resources. The light-initiated reactions of oxygenic photosynthesis in plants, algae and some bacteria occur in thylakoid membranes located in the plastids of the organism. Despite the same goal to synthesize carbohydrates and oxygen from carbon dioxide and water using the energy of light, these organisms possess a highly diverse structures of their photosynthetic apparatus determined by their habitat. The structural changes are observed at the molecular level, where pigment-protein complexes are involved in the initial steps of photosynthesis, as well as at the level of thylakoid membrane network, which appears to be highly dynamic system not only dependent on the environment conditions but also very diverse among different species. The elucidation of the structural changes and their function at different levels of the photosynthetic apparatus is crucial for the utilization of these processes for the benefit of the humankind to construct efficient artificial photosynthetic systems and improve the yield of crop plants.

In this thesis, the composition of the light-harvesting complexes from a relatively little studied algae is addressed. These studies led to the observation of interesting properties of carotenoid molecules which possess additional functional groups conjugated to the polyene chain. Therefore, these molecules are investigated isolated from the light-harvesting complexes by using experimental and theoretical methods, in order to reveal the characteristics which are able to tune the electronic and vibrational properties of carotenoids. And finally, several photosynthetic species are studied at the membrane level in order to obtain their thylakoid structure within the organism.

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