The activation and redox chemistry of small molecules such as CO, CO2, H2, formate, O2, NO, N2, and NH3 by metalloenzymes play important roles in vital processes such as the global carbon and nitrogen cycles, and as sources of energy or low-potential reducing equivalents in cellular environments (for example certain bacteria are capable of using CO2 as their sole C source, and H2 as their sole energy source). Despite the current urgent need for sustainable fuels and ‘green’ routes to chemical synthesis, detailed mechanistic understanding of how small molecule activation reactions are carried out in nature is often lacking. In part this is due to the high turnover frequencies achieved by the metalloenzymes which carry out these reactions, such as carbon monoxide dehydrogenase (CO2/CO, >2000 s-1), formate dehydrogenase (CO2/HCOO-, >112 s-1), and hydrogenase (H+/H2, >9000 s-1). New experimental tools are therefore required, capable of probing reactivity on fast, sub-turnover frequency timescales (ca. ps – ms).
Electrochemistry provides convenient control over the oxidation state of metalloenzymes and makes it possible to regulate enzymatic turnover. However, electrochemistry is most commonly applied to studies of steady-state kinetics, and is most suited to characterisation of long-lived catalytic intermediates. In contrast, photochemical triggers are widely used for sub-turnover mechanistic studies, offering valuable insight if catalysis can be initiated by light without triggering unwanted photochemical side reactions.
During this project we will develop a combined ‘photobioelectrochemical’ methodology coupled with a range of spectroscopic techniques in order to facilitate sub-turnover frequency studies of redox metalloenzyme mechanisms. Using this new approach we will identify and characterise short-lived catalytic intermediates and probe the fundamental coordination chemistry that equips metalloenzymes, Nautre’s ‘machines’, with such remarkable efficiency.
Entry requirements UK Bachelor Degree with at least 2:1 in a relevant subject or overseas equivalent.
English language requirements may apply
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How to apply To apply refer to https://le.ac.uk/study/research-degrees/funded-opportunities/epsrc-studentships
Eligibility: UK/EU (Residency Requirements for EU in accordance with UKRI)
3.5 Year funding:
RCUK Rate Stipend
• Ash, P.A., Carr, S.B., Reeve, H.A., Skorupskaite, A., Rowbotham, J.S., Shutt, R., Frogley, M.D., Evans, R.M., Cinque, G., Armstrong, F.A., Vincent, K.A.,'Shocking protein crystals into action: combining electrochemistry and infrared microscopy provides insight into [NiFe] hydrogenase mechanism', Diamond Light Source Annual Review, 2017/2018, page 84.
• Ash, P. A., Vincent, K. A., 'Vibrational Spectroscopic Techniques for Probing Bioelectrochemical Systems' in 'Biophotoelectrochemistry: From Bioelectrochemistry to Biophotovoltaics', Volume 158 of the series'Advances in Biochemical Engineering / Biotechnology', pp 75-110, Springer, 2016.
• Hidalgo, R., Ash, P.A., Healy, A.J., Vincent, K.A. 'Infrared Spectroscopy During Electrocatalytic Turnover Reveals the Ni-L Active Site State During H2 Oxidation by a NiFe Hydrogenase' Angew. Chemie. Int. Ed. 2015, 54, 7110-7113.