Researchers at the Louisiana State University Health Sciences Center have figured out how ATP is broken down in cells, providing for the first time a clear picture of the key reaction that allows cells in all living things to function and flourish.
Discovered some 80 years ago, adenosine triphosphate is said to be second in biological importance only to DNA. Each cell in the human body contains about a billion ATP molecules, and the power derived from the breakdown of them is used to deliver substances to their cellular homes, build needed complex molecules and even make muscles contract.
"ATP is the fuel of life. It's an energy currency molecule the most important source of chemical and mechanical energy in living systems," explains Sunyoung Kim, the associate professor who oversaw the research published Feb. 19 in the Journal of Biological Chemistry.
Scientists for decades have worked to understand the critically important reaction but, until now, did not know how proteins in a cell extract and use the energy from ATP.
In its original form, an ATP molecule has three phosphate groups. While it has been known for some time that, for ATP breakdown to occur, the third phosphate group must be attacked by a hydroxide, or a water molecule that has lost one of its protons, it was unknown what actually stripped away that proton, allowing the release of ATP's stores.
The team chose to investigate one particular family of protein machines that break down ATP the kinesins.
Kinesins are tiny biological machines that work a lot like car engines, Kim says, travelling up and down cellular roadways in support of several functions, such as cellular division and cargo transport.
"We picked kinesins because they're the simplest known motor proteins. Usually, proteins that break down ATP are very large and have a lot of moving parts for mechanical work." Kim says. "The simpler and the smaller the
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American Society for Biochemistry and Molecular Biology