Enzymes are Natures way of making things happen. They act as catalysts, meaning that chemical reactions which normally would take years to complete can be performed in a fraction of a second when an enzyme is present. At a more basic level, enzymes are proteins. Proteins are composed of long stretches of amino acids, all linked together end to end in a long chain. If a protein influences the rate of a chemical reaction (similar to a catalyst), the protein is called an enzyme. Not all proteins act as enzymes; some are just used as building materials, and some have no clear purpose.
While proteins without a clear purpose in the body may seem a bit useless, some have found a home performing functions that specifically require them not to influence their surroundings. One example is fluorescent marking. Organic chemists can chemically modify the structure of a naturally occurring protein to make it glow upon exposure to ultraviolet light. This phenomenon (called fluorescence) can be useful for determining whether or not a biological sample has incorporated any of the protein into its structure; the biochemist only needs to shine a UV lamp over the sample and observe whether or not it glows. However, this is still quite limited. Whether or not the fluorescent marker has been incorporated doesn’t shine any light (pun intended) on the activity of the true catalytic proteins (enzymes) in the sample.
Exciting news published in the science journal Chemical Communications now reports that an enzymatic protein has been discovered which is also fluorescent. Most importantly, the fluorescence changes upon the status of the protein. Proteins only become enzymes when their three-dimensional shape (a result of the long amino acid folding and twisting around itself) reaches the precise structure required by the reaction. The new protein, which is a type of enzyme known as a dehydrogenase, was collected from sea-based bacteria. When it is incorporated into a biological sample, its fluorescence can be observed using UV light and the extent of the fluorescence correlates to the activity of the protein.
This is a fantastic discovery, as scientists can now tell with a glance whether or not a given biological catalyst is still active, or if it has been destroyed or consumed by some side reaction. Even simple, straightforward catalysts such as bulk metal powders have to be continuously monitored with painstaking analyses in order to monitor their usefulness. You don’t want to throw a precious metal catalyst away before it reaches the end of its lifetime, but at the same time you don’t want to attempt a reaction if the catalyst is no good. The problem of catalyst analysis is magnified a thousand-fold with the immensely complicated structures of enzymatic proteins. Being able to monitor the enzymatic activity of a protein using a simple visual test is a huge step forward.
Scientists hope that this work will lead to future developments, as the very rapid nature of the analysis lends itself to a combinatorial approach where thousands of derivatives can be rapidly tested to find the one with highest activity. As we gather more understanding of this phenomenon, it is hoped that we will be able to modify other known enzymes to create a tie between their activity and the intensity of the fluorescence emitted.
The source of this article can be found at:
“A short-chain dehydrogenase/reductase from Vibrio vulnificus with both blue fluorescence and oxidoreductase activity”.
Karen Marie Polizzi, Desmond Antoine Moore and Andreas Sebastian Bommarius.
Chemical Communications, a publication of the Royal Society of Chemistry.