University of California, Berkeley, chemists have discovered the secret to the success of a jellyfish protein whose green glow has made it the darling of biologists and the subject of the 2008 Nobel Prize in Physiology or Medicine.
The researchers' study of green fluorescent protein (GFP) and the structural changes it undergoes when it fluoresces is the cover story of the Nov. 12 issue of the journal Nature.
GFP has replaced many dyes in biological studies because it is non-toxic and, when attached to a gene and inserted into an organism, serves as a bright, glowing confirmation that the gene has hit its target. Obtained originally from a bioluminescent Pacific Ocean jellyfish, the protein has been mutated and engineered to absorb and emit various colors.
The UC Berkeley chemists used extremely short laser pulses 20 millionths of a nanosecond, or 20 femtoseconds to take snapshots of GFP to determine the structural changes it undergoes when it fluoresces. Only a rapid, strobe-like laser can freeze atoms vibrating 100,000 times every nanosecond, or a hundred trillion times a second.
Their study not only sheds light on how GFP works, but also proves the value of new, ultrafast, pulsed laser techniques, specifically a method called femtosecond stimulated Raman spectroscopy, that take snapshots fast enough to freeze vibrating molecules and thereby distinguish the rapid steps involved in chemical and atomic reactions.
One of the researchers' goals is to understand the processes of absorption and emission of light in such detail that the light-absorbing molecule can be redesigned to more efficiently capture sunlight in photovoltaics, or solar cells.
"If you want to understand how a reaction occurs, you need to look at it as the chemical bonds change structure, which occurs over tens of femtoseconds," said Richard Mathies, UC Berkeley professor of chemistry and dean of the College of Chemistry. "With a f
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University of California - Berkeley