Instability of bioluminencence molecule explained

Oxyluciferin, the bioluminescent compound that puts the fire in firefly, is formed by the reaction of the protein luciferin with oxygen to produce the light emitting oxyluciferin, a reaction catalyzed by the enzyme luciferase. Though oxyluciferin is used extensively in research, for example as an indicator of genetic transformation, it is very unstable, decaying into other products before it can be isolated.

Two hypothestical pathways have been proposed to explain for this instability, but neither idea is supported by evidence, according to a study by team of researchers, including Naba Nath and Pance Naumov of the New York University in Abu Dhabi, and published by the journal Angewandte Chemie. Instead, the authors propose a third way

First, they chemically synthesized oxyluciferin and, using nuclear magnetic resonance spectroscopy and X-ray crystallography, identified bisoxyluciferin as the side product of the reaction. Bisoxyluciferin is a dimer of two forms of oxyluciferin that exist in equilibrium in aqueous solution. Contrary to what was thought, the presence or absence of oxygen had no effect on the stability of oxyluciferin.

Having determined the formation of bisoxyluciferin as the cause of oxyluciferin's instability, they tweaked the reaction conditions by cooling the temperature and shortening the time to minimize the coexistence of the two forms of oxyluciferin that react together. This resulted in oxyluciferin with an unprecedented purity of over 99%.

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