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Title: Structural and functional characterisation of magnesium protoporphyrin IX chelatase from Thermosynechococcus elongatus
Author: Marklew, Christopher James
ISNI:       0000 0004 2735 8176
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2012
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The production of chemical energy from light energy is arguably the most important reaction known. Nearly all life depends on energy derived from light and it is by this process that the atmosphere of our planet was oxygenated. Chlorophyll is the pigment that absorbs light and donates an electron initiating the process of photosynthesis. This highly complex molecule is the result of many chemical reactions collectively known as chlorophyll biosynthesis. Chlorophyll is a modified tetrapyrrole and shares a common synthetic pathway to vitamin B12, Siroheam and haem. Photosynthetic organisms need both chlorophyll and haem, and the branch point they share, committing to the production of either is thought to be highly regulated. The common precursor to both pigments is protoporphyrin IX and the fate of the macrocycle depends on which divalent metal ion is inserted into the tetrapyrrole. The insertion of Fe2+ by ferrochelatase commits to the production of haem whereas the insertion of Mg2+ by magnesium chelatase commits to the production of chlorophyll. The magnesium chelatase is comprised of three subunits that are all essential for activity and are known as ChlH (~150 kDa), ChlD (~75 kDa) and ChlI (~40 kDa). It is known that the H protein binds both the tetrapyrrole substrate and product of the reaction. The I and D subunits are thought to be the catalytic element of the enzyme and once a H•substrate complex is formed, this binds with an ID complex to initiate the reaction. This work will focus on the structural and functional characteristics of a thermophilic magnesium chelatase (from Thermosynechococcus elongatus) which have never been previously studied.
Supervisor: Hunter, C.Neil Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available