Oxford, UK-- Infrared (IR) spectroscopy using lasers is helping to deliver snapshots of chemical changes in enzymes at the pico- or even femto-second scale. These infrared methods should capture fast chemical reactions occurring at metal centers in proteins, revealing information about intermediate species formed during catalytic reactions.
"Many groups are trying different approaches, but at Oxford, we are combining infrared spectroscopy with electrochemistry so that we can control the state of metal-containing proteins at electrodes and, at the same time, measure infrared spectra to obtain information on the structure and function of the protein," says Kylie Vincent of Oxford University’s Department of Chemistry. "This should provide structural insight into states of metal-containing proteins that are only formed at precise potentials - revealing details of reactions occurring during respiration, metabolism or photosynthesis."
Because metal centers in proteins also bind small molecules that send signals in biological systems, infrared spectroscopic experiments should help to understand and control these types of processes. These metal centers are hives of industry at a microscopic scale, with metals often held in a special protein environment where they may be assembled into intricate clusters inside proteins.
"Nearly half of all enzymes require metals to function in catalysing biological reactions," says Vincent. "Both the metal and the surrounding protein are crucial in tuning the reactivity of metal catalytic centers in enzymes."
Understanding the effects of the protein environment is important because metal-containing proteins are involved in many biological energy cycling reactions, including the oxidation or production of hydrogen and the conversion of carbon dioxide into organic carbon molecules.
Kylie has written a review of advances in this area of chemistry published in this week’s Philosophical Transactions of the Royal Society A. The article explores how chemists are looking beyond X-ray based techniques to find new ways to capture enzymes at work.
"X-ray crystal structures of metal-containing proteins provide snapshots of the positions of atoms, but proteins are dynamic systems and structural changes are often crucial to their function," Vincent explains.