UPTON, NY Using two simultaneous light-based probing techniques at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory, a team of researchers has illuminated important details about a class of enzymes involved in everything from photosynthesis to the regulation of biological clocks.
The interdisciplinary team has a broad interest in flavoproteins, which were first discovered in the 1930s and derive from riboflavin, or vitamin B2. These proteins are now known to catalyze a wide range of biochemical reactions, including those that use molecular oxygen (O2) to help convert food into energy in animals, plants, fungi, and in some types of bacteria a process known as oxygen activation.
Although scientists have determined more than 1,200 crystal structures of flavoproteins, they've been blind to exactly what oxygen activation looks like within these enzymes. Specifically, researchers have been unable to determine the structure of the flavoprotein's reactive oxygen intermediate, a molecular complex that often forms halfway through important biochemical reactions. These intermediates possess high chemical potential energy, which is necessary to complete many critical but difficult-to-catalyze reactions in biology. Such intermediates typically have a lifetime of only a few milliseconds and are therefore very hard to observe using traditional synchrotron methods.
"Flavoproteins represent one of only a handful of ways that nature activates molecular oxygen, a process that's important for all life on the planet," said Brookhaven biophysicist Allen Orville. "We've determined structures of some oxygen intermediates involved in several important enzymes that assist in this process. But no one has ever seen an oxygen intermediate attached to the flavin. Until now."
As reported in the January 9, 2009, online edition of Biochemistry, Orville and colleagues from Georgia State University, Georgia Institute of Techno
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DOE/Brookhaven National Laboratory