Adenosine triphosphate (ATP) is one of the most important nucleotides present in living organisms because it stores and delivers energy from the metabolizing of food. Without ATP, for example, humans would be unable to use their muscles because it serves as the source of energy for their movement.
The compound ATP was discovered by Fritz Lipmann, a German-American biochemist at the Rockefeller Institute for Medical Research. In 1937 Lipmann had discovered, almost by accident, that phosphates were somehow important to the metabolic process. He was uncertain exactly what role they played, but believed it had something to do with the delivery of energy to the body's cells. In 1941, he finally found answers to some of the questions he had been asking. He found a molecule that released a low-energy phosphate--adenosine monophosphate--and discovered that, during the course of carbohydrate metabolism, the molecule picked up two energy-rich phosphate bonds and became ATP, a high-energy configuration that was able to release small traces of energy, when needed, to cells throughout the body. His discovery led to the recognition of ATP as being of crucial importance in the handling of energy by the body because of its versatility in converting nutrients and carbohydrates from foods into energy and transporting it to the muscles.
In 1947, soon after Lipmann's discovery, Alexander Robertus Todd synthesized ATP. As professor of chemistry at the University of Manchester, he had been studying the chemistry of the nucleic acids with the nucleotides. In 1944, he moved on to Cambridge University and three years later, he successfully synthesized the compounds in ATP. Todd's work on these and other nucleic acid compounds clarified the general chemistry of the nucleic acids.
The next advancement in the understanding of ATP was made by Carl Sagan, who in 1963 detected its formation while working with Cyril Ponnamperuma and Ruth Mariner in NASA's exobiology division. Concerned with the origin of life, their group attempted to simulate the primordial conditions of the planet that gave rise to nucleic acids, the building blocks of proteins and ultimately of living cells. After detecting the formation of ATP, he was able to describe how a store of the compound could have built up in primordial oceans to the point where it could provide energy for the production of life. Soon after, Ponnamperuma demonstrated that ATP could be synthesized by exposing a certain mixture of chemicals to ultraviolet light, thus proving that solar energy could be converted into a chemical energy source for primordial life.
The latest advancement in ATP research is the result of research that started in the 1950s. In 1957, Jens Christian Skou at the University of Aarhus, Denmark discovered an ion-transporting enzyme which he termed Na,K-ATPase. This enzyme maintains the balance of sodium and potassium ions in the cell by pumping sodium ions out and potassium ions in. This was the first description of an enzyme that moves substances through cell membranes. This sodium-potassium pump is important because it is the largest consumer of ATP in living cells. Meanwhile, Dr. Paul Boyer at UCLA was performing his own research on ATP. In 1979, he proposed a mechanism for the production of ATP from ADP in the cell's mitochondria without expending energy. He postulated that the ATP production mechanism actually spins like a water wheel, creating ATP without energy loss. This theory was met with speculation until in 1994 Dr. John Walker at the Medical Research Council Laboratory of Molecular Biology in Cambridge discovered the three dimensional shape of the enzyme involved in the production of ATP, called ATP synthase. Using X-ray crystallography, he discovered that the enzyme is shaped much like a barrel. Protons flow through the membrane and makes a portion of the enzyme spin, taking up materials such as ADP and phosphates and pushing out ATP. This spinning model of the enzyme ATP synthase proved Boyer's theory of the mechanism of ATP production without energy loss, and for their work, Skou, Boyer, and Walker shared the 1997 Nobel Prize in Chemistry.
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