Jens Christian Skou: Nobel Prize in Chemistry 1997 - PDF

Jens Chr. Skou-Lucky Choices The Story of my Life in Science Prof. Varadhan SKM Department of Applied Mechanics and Biomedical Engineering In this class… 1. Jens Christian Skou 2. Nobel Prize 3. Na+ - K+ - ATPase 4. The Influence of Some Cations on an Adenosine Triphosphatase from Peripher...

Jens Chr. Skou-Lucky Choices The Story of my Life in Science Prof. Varadhan SKM Department of Applied Mechanics and Biomedical Engineering In this class… 1. Jens Christian Skou 2. Nobel Prize 3. Na+ - K+ - ATPase 4. The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves a) Introduction b) Experimental c) Results Reference Jens Christian Skou The Nobel Prize in Chemistry 1997 Born: 8 October 1918, Lemvig, Denmark Died: 28 May 2018, Aarhus, Denmark Affiliation at the time of the award: Aarhus University, Aarhus, Denmark Prize motivation: “for the first discovery of an ion-transporting enzyme, Na+, K+ -ATPase” Creator: Lars Kruse, https://commons.wikimedia.org/wiki/File:Skou2008.j pg , CC BY-SA 2.5 Jens Christian Skou Early Life and Family Background: - Born on October 8, 1918, in Lemvig, Denmark, into a wealthy family. - Father, Magnus Martinus Skou, and uncle Peter Skou were timber and coal merchants. - Oldest of four children with two brothers and one sister. - Father's death at age 12 from pneumonia did not change the family’s financial situation as the business continued with the mother as a passive partner. - Attended boarding school (gymnasium) in Haslev for three years. Education: - Medical student at the University of Copenhagen starting in 1937, after being convinced by a friend. - Medical course took 7 years, including both pre-clinical and clinical subjects. - Graduated in 1944, during WWII. Jens Christian Skou World War II Impact: - Lived through the German occupation of Denmark beginning in 1940. - The occupation affected freedom of speech and daily life. - Became involved in medical education and resistance activities during the war. - Medical teaching continued despite challenges; classmates faced dangers including betrayal by a German informer. Early Career and Research: - Internship at Hjørring Hospital, developed an interest in surgery. - Continued clinical training in Aarhus. - Shifted to physiology research at Aarhus University in 1947, focusing on local anaesthetics. - Married Ellen Margrethe Nielsen in 1948; faced the loss of their first daughter and had two more daughters, Hanne and Karen. Jens Christian Skou Professional and Personal Life: - Became a social democrat, valuing welfare systems and social equality. - Built a house in Risskov, a suburb of Aarhus. - Emphasized family life, balancing work and family time. - Enjoyed sailing, skiing, and other leisure activities with his family. Academic Career: - Thesis on local anaesthetics published in 1954. - Identified the sodium-potassium pump in 1957, shifting research focus to active transport of cations. - Faced challenges due to limited funding in the early years but later secured significant grants. - Became a professor and chairman in 1963, expanding the institute’s staff and research scope. - Implemented modern teaching methods and problem-oriented learning. Jens Christian Skou International Collaborations and Recognition: - Established connections with scientists worldwide, including NIH funding. - Participated in and organized international meetings on the Na +,K+-ATPase. - Travelled extensively for lectures and conferences, gaining cultural experiences and friendships. Later Years and Retirement: - Moved to the Biophysics chair in 1977, focusing the department on Na +,K+-ATPase research. - Retired in 1988, continued working on kinetic models for the pump using computers. - Enjoyed a relaxed and collaborative research environment in his later career. Overall Impact: - Contributed significantly to the understanding of the Na +,K+-ATPase. - Balanced a successful scientific career with a fulfilling family life. - Valued collaboration, education, and social responsibility throughout his life. Nobel Prize The sodium–potassium pump main mechanism for active ion transport across cardiac cell membranes, essential for processes like nerve signaling, heart contractions, and kidney function. It maintains the sodium and potassium gradients crucial for cardiac cell electrophysiology. Its dysfunction is linked to diseases such as ischemia and heart failure. Creator: Professor Jens Christian Skou's discovery of the enzyme sodium, potassium- https://commons.wikimedia.org/wiki/File:The_Gold_Nob el_Prize_medal_%28ann19061a%29.jpg , CC BY 4.0 stimulated adenosine triphosphatase (Na⁺, K⁺-ATPase) balances sodium and potassium ions in cells, earning him a share of the 1997 Nobel Prize in Chemistry. The other half was awarded to Professor Paul D. Boyer and Dr. John E. Walker for their work on the enzymatic mechanism of ATP synthesis. Na+ - K+ - ATPase The sodium-potassium pump (Na,K-ATPase) is an enzyme found in the membrane of animal cells that helps maintain the proper concentration of sodium and potassium ions inside and outside of the cell. The pump moves three sodium ions out of the cell for every two potassium ions it brings in, against their concentration gradient. This process is an example of active transport, which Creator: https://commons.wikimedia.org/wiki/File:0308_Sodium_Potassiu m_Pump.jpg requires energy in the form of ATP. , CC BY 4.0 Na+ - K+ - ATPase- Research The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves Introduction Stimulation of a nerve influx of sodium ions, increasing intra-axonal sodium concentration. Energy-dependent outward transport of sodium ions against an electrochemical gradient Normal conditions Experiments by Hodgkin and Keynes with giant axons from Sepia officinalis and Loligo forbesi species dinitrophenol, azide, and cyanide inhibit this active sodium transport and oxidative phosphorylation in mitochondria Link between energy-rich phosphate esters and sodium ion transport. Libet and Abood and Gerard found adenosine triphosphatase (ATPase) in the sheaths of giant axons, indicating a potential role in sodium ion transport. Libet's work the ATPase is calcium-activated, while Abood and Gerard magnesium-activated and located in submicroscopic particles. Na+ - K+ - ATPase- Research The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves Introduction In peripheral rat nerves both calcium- and magnesium-activated ATPases, with distinct localizations in mitochondria and submicroscopic particles, respectively. In studies on leg nerves from the shore crab similar ATPase activation by calcium and magnesium The investigation examined the effect of sodium, potassium, magnesium, and calcium cations on enzyme activity. Na+ - K+ - ATPase- Research The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves Experimental The ATPase enzyme was prepared from the leg nerves of the shore crab (Carcinus maenas) using homogenization and differential centrifugation. The isolated nerves were washed and homogenized in a buffered sucrose solution to avoid contamination with alkali metal ions. The homogenate underwent multiple centrifugation steps to remove fragments, stroma, mitochondria, and submicroscopic particles, resulting in a final enzyme solution containing half to two-thirds of the original activity. The enzyme was unstable, losing half its activity within 3-4 days when stored at 4-5°C. ATP and ADP were converted to free acids and neutralized for use. Na+ - K+ - ATPase- Research The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves Experimental The enzyme activity was determined in a reaction mixture buffered with histidine, with ATP and cations added as needed. Experiments were conducted at 36°C, and the reaction was started by adding the enzyme, followed by incubation. The ATP hydrolysis reaction was stopped by adding trichloroacetic acid, and inorganic phosphate was measured. Small amounts of sodium and potassium were present in the reaction mixture from the enzyme solution and ATP. Enzyme activity was expressed as the amount of phosphate split from ATP in 30 minutes.  Na+ - K+ - ATPase- Research The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves Results When the substrate is ADP, no inorganic phosphate is released. In the presence of ATP, hydrolysis stops after one phosphate group is split off, with a pH optimum at 7.2. (Fig 1 and Fig 2) Enzyme activity is zero without cations or with only K+ or Ca++. Fig 1 The addition of Na+ produces minimal activity, while Mg++ shows Fig 2 slight activity, peaking at 3 mM/l. (Fig 3) Enzyme activity increases with the addition of Na+ to a Mg++- containing mixture, peaking at 6 mM/l Na+ before declining at Fig 3 higher concentrations. (Fig 4) Fig 4 dapted from: The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves  Na+ - K+ - ATPase- Research The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves Results K+ addition to a Mg++ containing mixture doesn't affect enzyme activity, while Ca++ inhibits it. (Fig 5) When both Mg++ and Na+ are present, K+ increases enzyme activity, peaking and then decreasing at higher K+ concentrations. High K+ concentrations inhibit Na+ dependent but not Mg++ dependent activity. Maximum activity in the presence of K+ increases with Na+ Fig 5 concentration, with optimal K+ concentration matching Na+ concentration. dapted from: The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves  Na+ - K+ - ATPase- Research The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves Results Adding K+ alters the relationship between enzyme activity and Na+ concentration. (Fig 6) Without K+, activity peaks at 6 mM/l Na+ and decreases with more Na+. With 3 mM/l K+, activity increases with Na+ concentration until leveling off. High K+ concentrations lead to low activity in the absence of Fig 6 Na+, with small Na+ amounts inhibiting this activity but higher Na+ concentrations having the usual activating effect. dapted from: The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves  Na+ - K+ - ATPase- Research The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves Results Ca++ inhibits Mg++-dependent activity and also inhibits systems containing Mg++ and Na+ or Mg++, Na+, and K+. Fig 8 (Fig 7) Fig 7 The optimal Mg++ concentration is 3 mM/l with Mg++ or Mg+ + and Na+, rising to 6 mM/l with K+ and further with Ca++ addition. (Fig 8) The activating effect of Na+ is proportional to the Mg:Ca ratio. Low Na+ concentrations inhibit Mg++-dependent activity in the presence of high K+ and Ca++. (Fig 9 and Fig 10) Fig 9 Fig 10 dapted from: The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves  Na+ - K+ - ATPase- Research The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves Results Li+ increases activity in systems with Mg++ and Na+, similar to K+ but with a weaker effect at low concentrations and a stronger effect at high concentrations. (Fig 11) Fig 11 dapted from: The Influence of Some Cations on an Adenosine Triphosphatase from Peripheral Nerves Na+ - K+ - ATPase- Research Enzymatic Basis for Active Transport of Na+ and K+ Across Cell Membrane In 1965, in a review paper Jens Chr. Skou concluded that the enzyme system fulfilled the following requirements for a system responsible for the active transport across the cell membrane: 1) it is located in the cell membrane; 2) on the cytoplasmic side, it has a higher affinity for Na than for K+; 3) it has an affinity for K+ on the extracellular side, which is higher than for Na; 4) it has enzymatic activity and catalyzes ATP hydrolysis; 5) the rate of ATP hydrolysis depends on cytoplasmic Na as well as on extra- cellular K; 6) it is found in all cells that have coupled active transport of Na+ and K+; 7) the effect of Na and of K on transport in intact cells, and on the activity of the isolated enzyme, correlates quantitatively; and 8) the enzyme is inhibited by cardiac glycosides, and the inhibitory effect on the active fluxes of the cations correlates with the inhibitory effect on the isolated enzyme system. The enzyme was named the Na- and K+- activated ATPase, or Na+, K+- ATPase. Conclusion Nobel Lecture Quote: Looking for the answer. You hunt it, You catch it, You fool Yourself; The answer, Is always, A step ahead. J.C.S References 1. Lucky Choices The story of my Life in Sciences- Jens Christian Skou 2. Skou, J. C. (1957). The influence of some cations on an adenosine triphosphatase from peripheral nerves. Biochimica et biophysica acta, 23, 394-401. 3. https://www.biokemi.eu/page-18244 4. The Identification of the Sodium Potassium pump- Nobel Lecture by Jens C. Skou 5. https://www.nobelprize.org/prizes/chemistry/1997/skou/facts/ 6. SKou, J. C. (1965). Enzymatic basis for active transport of Na+ and K+ across cell membrane. Physiological reviews, 45(3), 596-618.