Jens C. Skou

Professor Jens Christian Skou (1918- )

Nobel Laureate in Chemistry in 1997

"for the first discovery of an ion-transporting enzyme, Na⁺ K⁺ ATPase"

In 1997, Jens Skou became the fourteenth person from Denmark to win the Nobel Prize. The Nobel Prize that year focused on researchers who analyzed enzymes associated with the energy molecule adenosine triphosphate, or ATP. Half of the prize was split between Paul D. Boyer and John E. Walker, researchers who discovered the mechanism for ATP synthesis. The other half went to Skou for discovering the sodium-potassium ATPase pump (Na⁺ K⁺ ATPase), an enzyme vital for cellular ion transport. Quite an achievement for a man who originally had no interest in scientific research.

His Early Life and Education

Jens Skou was born on October 8, 1918 in Lemvig, a small town in Denmark. His father and brother were both successful timber and coal merchants, making his family rather wealthy. From a young age he enjoyed the outdoors. He liked to play games with his siblings and friends in the family’s timber yard. He also developed a love for boating at his family’s large summerhouse on the North Sea coast of Denmark. Sadly, his father died from pneumonia when he was 12, leaving his mother to raise the children alone.

When Skou was 15 he went to a boarding school in Haslev. His favorite subjects were science and math and he enjoyed various sports and scouting. He was very close to his family and every school vacation he went home to spend time with them. When he graduated from the boarding school in 1937 he was unsure about what to do next. One of his tennis partners convinced him to study medicine and become a doctor. Skou moved to the capital city of Copenhagen and began his training at the University of Copenhagen. He was originally not that happy about living in such a large city. However, he quickly developed an appreciation for all the different art galleries and concerts that were offered there.

World War II started while Skou was studying in Copenhagen. This quickly led to the German occupation of Denmark in 1940. Many Danes were ashamed at how quickly their government had fallen. Freedom of speech was severely restricted, however medical teaching was not affected and Skou was allowed to continue with his education. His family’s summer home was taken over by German troops. When he went home to Lemvig during his summer vacation he found that the German army was also occupying that home as well. His mother had stoically refused to leave and Skou managed to convince the Germans to leave the house while his siblings were home for the summer. He got his medical degree in 1944 at the age of 26. Many of the teachers that would have given the final tests had been forced to go underground, leaving others to take their place. The new graduates had to assemble at a secret location to take the Hippocratic Oath. After Germany was defeated by allied forces it withdrew from Denmark in 1945.

Skou dreamed of becoming a surgeon and had an interest in anesthesiology. After his vacation he started a surgical internship at Hjørring hospital in northern Denmark and worked there for two years. During this time he started studying local anesthetics and how they worked. This proved to be a major turning point in his life. He became so interested in science that he stopped his work as a surgeon and spent full time as a researcher. He started his new career by pursuing a doctorate at the Department of Physiology at the University of Aarhus in 1947. He had no formal scientific training and had to learn how to approach a problem on his own. He earned a doctorate degree focusing on anesthetics in 1954. Afterward he stayed with the university and became a professor. The university was only 19 years old at the time and money allocated for research was scarce. On top of that, Skou had to spend time away from the laboratory teaching medical students. His pay was also very low, so he supplemented his salary by moonlighting as an on-call doctor.

In 1963 Skou was appointed as the chairman of the Physiology Department. During this time more money had been allocated to the university and more modern equipment was purchased. Additional faculty and researchers were hired, which meant Skou had fewer teaching responsibilities. However, he didn’t exactly find his administrative duties exciting. In 1972 Skou was happy to hear that the chairman position was to be elected instead of appointed. Hoping to step down from his duties, he was surprise when his peers immediately elected him to be the chairman. He kept the position for a while before happily handing the tedious responsibilities over to an elected board. In 1977 Skou was again promoted to the chair of the Biophysics Department at the University of Aarhus. This department was much smaller and Skou was responsible for only seven researchers, didn’t have teaching responsibilities, and had far less administrative duties.

In 1988 Skou had to retire from the university because he turned 70, the maximum age of retirement. He because an Emeritus Professor and continues to work every day at the university.

His Discovery that Led to the Nobel Prize

The concept of ion transport through cells had been known for some time. In the 1920s it was discovered that the ion composition within living cells is different from its surroundings. Two scientists, Keynes and Hogkin, discovered in the 1950s that sodium ions quickly enter a stimulated nerve cell, followed by an influx of potassium ions. These ion concentrations were then restored to their normal levels, a process that appeared to require energy in the form of ATP. However, it was unknown how the sodium and potassium ions were transported in or out of the cell.

Skou learned about this ion transport while he was studying nerves and their response to anesthesia. He speculated that the transport required a change in the proteins present in the cell membrane. Skou spent many years searching for an enzyme present in the nerve cell membrane that used ATP to transport sodium and potassium ions. He started his search in 1953 at a marine biology station in the Atlantic near Boston. There he analyzed the nerves of squid, which are much larger than human nerves and therefore easier to study. During that time he read about an enzyme present in the membrane of squid cells that uses ATP. He thought this ATPase might also be the enzyme responsible for sodium and potassium ion transport. He returned to the university in 1954 and tried to find the enzyme in crab nerve cells. Two unlucky lab technicians had the messy job of killing the crabs that arrived daily and dissect them for the nerve cells. Skou found that the ATP-dependent enzyme in the squid was also present in crabs. More importantly, he discovered that sodium and potassium ions affected the activity of the enzyme.

Skou concluded that this enzyme was the same one responsible for ion transport and in 1956 published an article about his discovery titled:

”The Influence of Some Cations on an Adenosine Triphosphate from Peripheral Nerves”

He was too cautious to use the word “pump” in the title to describe the enzyme. However, this meant that researchers who worked on ion transport never saw the original paper. His discovery was not fully recognized until he gave a presentation about the enzyme at a large scientific conference in Vienna in 1958. From there, research concerning the Na⁺ K⁺ ATPase pump exploded. The first international meeting for the Na⁺ K⁺ ATPase was held in New York in 1973. Skou wasn’t awarded the Nobel Prize until forty years after the discovery of the pump. Additional research he did on the enzyme was thought to contribute to him being chosen for the award.

The Na⁺ K⁺ ATPase pump is a vital part of the cellular ion transport. It is found in the cell membrane of animals and plants and uses ATP to maintain the balance of sodium and potassium ions in the living cell. The pump uses about a third of all the ATP synthesized in a resting organism. It continually pumps sodium ions out of the cell and potassium ions into the cell to maintain a correct ionic balance. An incorrect balance will quickly result in cell death. The pump contributes to three cellular functions. First, potassium that has been transported into the cell by the pump continually leaks out. This results in the inside of the cell membrane having a negative charge compared to the outside. This difference in charge across the membrane is required for nerve signals to move along nerve cells. Second, the pump forms a sodium gradient between the cell and external environment. This gradient is the main force that helps the cell take up nutrients such as glucose and amino acids. Finally, the pump is required to maintain a normal cell volume. If the pump stops working then the cell will swell because of the unchecked sodium ions entering the cell. The discovery of the Na⁺ K⁺ ATPase pump led the way for the discovery of other ion pumps, including the calcium ATPase pump and the H⁺ K⁺ATPase pump.

His Personal Life

When Skou was working at Hjørring he fell ill and had to stay in the hospital. While recovering he met a nurse named Ellen Margrethe Nielsen. The two fell in love while listening to nighttime English radio war broadcasts and were married in 1948. They moved into a home in the suburbs near the university. The couple had two daughters, one in 1952 and one in 1954. Skou often helped with the housework while his wife served on political committees. They recently celebrated their fiftieth wedding anniversary.

Skou is a strict family man, staying in the laboratory only for normal hours on weekdays in order to spend more time with his family. They built a summerhouse where he passed his love for sailing on to his daughters. The whole family also went cross country skiing every winter on an eight-day tour in Norway. When not in the outdoors Skou enjoys listening to classical music and reading. He enjoys his spare time after retiring and uses it to go fly fishing and spend time with his grandchildren.

His Awards

• The Leo award
• The Novo award
• Consul Ernst Carlsen's award
• Anders Retzius's gold medal. The Swedish Medical Association
• Eric K. Fernströms Store Nordiske Pris
• The Prakash Datta medal. The Federation of European Biochemical Societies
• The Nobel Prize in Chemistry, 1997

Sources

• http://www.nobel.se/chemistry/laureates/1997/skou-autobio.html
• http://www.au.dk/uk/sun/biofysik/nobel/sectiona.htm
• http://www.au.dk/uk/sun/biofysik/nobel/sectionb.htm
• http://www.au.dk/uk/sun/biofysik/nobel/sectionf.htm