The development of a method for solubilisation of dark etioplast and the regulation of Chlorophyll binding to the Cytochrome b6f complex during deetiolation.

Abstract

During photosynthesis light energy in used to make ATP, during this process cytochrome b6f acts as a link between photosystem I and II. Cytochrome b6f received electrons from photosystem II and passes them to photosystem I, and play a key role in the formation of ATP form ADP. The p-side quinol deprotonation-oxidation reactions within the cytochrome b6f complex were found to be involved in generating reactive oxygenic species. Within the quinol oxidation site, a chlorophyll molecule has been found. This Chlorophyll molecule have been suggested to perform a structural, non-photochemical function by enhancing the rate of formation of the oxygen species. Similarities between unique features in Cytochrome bc1 and have been found in cytochrome b6f. These features could provide the key information to understand the evolution and regulation of electron transfer process in the oxygenic photosynthesis. One of the objectives of this thesis is to investigate the exchange of protochlorophyllide bound to cytochrome b6f complex in etiolated plants against chlorophyll. Previous instigations have shown that cytochrome b6f isolated in the dark can bind to chlorophyll a in vitro, however it is still unknown if cytochrome b6f can bind to chlorophyll b. Special focus in this thesis is to investigate the binding of chlorophyll b to cytochrome b6f complex.

The main focus of this thesis however, has been to develop a method that can be used in order to investigate the binding of chlorophyll b to cytochrome b6f. The method for solubilisation were in the developmental phases at the start of this thesis, and one of the objectives have been to optimize and standardize the method of solubilisation of dark etioplasts.