Skou, Jens Christian (1918-) is a Danish physiologist who won half the 1997 Nobel Prize in chemistry for his pioneering work on an enzyme (a substance that speeds up chemical reactions in living cells) involved in the process of energy conversion in living organisms. American chemist Paul Delos Boyer and British chemist John Ernest Walker shared the other half of the prize.

The work of all three scientists involved the chemical adenosine triphosphate (ATP), which is found in every living thing. It plays a central role in the conversion of nutrients into energy used in all life processes. The ATP molecule is composed of a nitrogen-containing compound, adenosine, plus three phosphate groups bonded in sequence. A phosphate group consists of one phosphorus atom and four oxygen atoms.

Skou was born Oct. 8, 1918, in Lemvig, Denmark, the oldest of four children of Magnus Martinus Skou and Ane-Margrethe Skou. Lemvig lay on a fjord that led to the North Sea. Skou's father operated a timber and coal business with his brother. When Skou was 12 years old, his father died of pneumonia and Skou's mother maintained the partnership with his uncle. Ane-Margrethe never remarried. When he was 15, Skou went to boarding school because there was no high school in Lemvig. His favorite subjects were science and mathematics.

Skou went on to train as a doctor at the University of Copenhagen. He received his medical degree in 1944, but not before living through Denmark's difficulty in World War II (1939–1945). Beginning in 1940, the Germans occupied Denmark. Fortunately for Skou, they did not interfere with the study of medicine. However, the Germans armed the North Sea coast against invasion from the Allied forces. Access to the coast was forbidden to Danes, and the Skou summer house was occupied. Skou managed to take his exams in 1944, though some of his teachers had gone underground and been replaced by others. The medical graduates were not permitted to assemble for the traditional signing of the Hippocratic oath, but they did so one at a time at secret locations. The Germans took over his mother's house, but Skou convinced the local German commander to move the occupants out during the holidays.

In 1947, Skou joined the Institute for Medical Physiology at Aarhus University, in Aarhus, Denmark's second largest city. Skou received a doctorate in 1954. He became a professor of physiology at Aarhus in 1963 and was professor of biophysics there from 1977 to 1988.

After the discovery of ATP in 1929, scientists worked to explain its role in energy production and how it is formed in the cell. The basic functions of organisms, such as the beating of the heart, the contractions of muscles, and the transmission of nerve impulses, depend on ATP.

In the 1950's, Skou carried out research with cell membranes from the nerves of a crab. He discovered Na+, K+-ATPase, an enzyme that forces sodium and potassium across the membranes—sodium out of the cells and potassium into the cells. In other words, Na+, K+-ATPase maintains the balance of sodium (Na+) and potassium (K+) ions in cells. This mechanism, which derives its energy from ATP, is essential for nerve stimulation to move along a nerve fiber or muscle cell.

In 1957, Skou was the first to describe this ion transport, called a molecular pump, or a sodium potassium pump. Since then, several similar ion pumps have been demonstrated. These ion pumps work all the time in our body. If they did not, the cells would swell up, even burst, and we would lose consciousness. About one-third of the ATP that the human body produces is used to drive ion pumps.

In 1997, Boyer and Walker won the Nobel Prize for their discovery of the mechanism underlying the synthesis of ATP. Skou received it for his discovery of the ion-transporting enzyme, Na+, K+-ATPase.