Jens Christian Skou: The 1997 Nobel Prize Winner in Chemistry

The 1997 Nobel Prize in Chemistry
to
Professor Jens Christian Skou

The Royal Swedish Academy of Sciences has awarded the 1997 Nobel Prize in Chemistry with one half to Professor Jens Christian Skou, University of Aarhus, Denmark for the first discovery of an ion-transporting enzyme, the Na⁺,K⁺-ATPase. This enzyme maintains the balance of sodium and potassium ions in the living cell.

The other half is shared by Professor Paul D. Boyer, University of California, Los Angeles, USA, and Dr. John E. Walker, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom for their elucidation of the enzymatic mechanism underlying the synthesis of adenosine triphosphate (ATP).

Professor Skou made his pioneer work at the Department of Physiology, University of Aarhus, where Professor Skou was employed as an assistant professor in 1947 and from 1963 as a full professor until he in 1978 was nominated to become the professor of biophysics at this university without advertising the post.

Professor Skou published the discovery of the Na⁺,K⁺-ATPase in 1957 in Biochimica et Biophysica Acta vol. 23, pp. 394-401:

SUMMARY Leg nerves from the shore crab (Carcinus maenas) contain an adenosine triphosphatase which is located in the submicroscopic particles. The influence of sodium, potassium, magnesium and calcium ions on this enzyme has been investigated.
     The presence of magnesium ions is an obligatory requirement for the activity of the enzyme. Sodium ions increase the activity when magnesium ions are present. Potassium ions increase the activity when the system contains both magnesium and sodium ions. Potassium ions in high concentration inhibit that part of the activity which is due to Na⁺, while the activity due to Mg⁺⁺ is not affected. Calcium ions inhibit the enzyme under all conditions.
     When Mg⁺⁺ or Mg⁺⁺ + Na⁺ are present in the system, the optimum magnesium concentration is equal to the concentration of ATP. If potassium ions are added, the optimum magnesium concentration is doubled. If calcium ions are also added, the optimum magnesium concentration becomes still higher, and it increases with the calcium concentration.
     A majority of these observations may be explained by assuming (a) that the substrate most readily attacked by the enzyme is sodium-magnesium-ATP, (b) that potassium ions stimulate the enzyme directly, and (c) that an increase in the concentration of potassium ions leads to a displacement of sodium ions from the substrate and accordingly to an inhibition of the reaction.
     If the system contains the four cations in concentrations roughly equal to those in the crab-nerve axoplasm, an increase in the sodium concentration as well as a decrease in the potassium concentration will lead to an intensification of the enzyme activity. This observation, as well as some other characteristics of the system, suggest that the adenosine triphosphatase studied here may be involved in the active extrusion of sodium from the nerve fibre.

Reprinted from Biochimica et Biophysica Acta, Vol. 23, Jens Christian Skou, The Influence of some Cations on an Adenosine Triphosphatase from Peripheral Nerves, pp. 394-401, Copyright (1957). With permission from Elsevier Science.

As the source of the enzyme, professor Skou used nerves (Fig. 1 and 2) isolated from the legs of the shore crab (Carcinus maenas) (Fig. 3).

Fig. 1.	Fig. 2.
Fig. 3.

Professor Skou has described his early work in the paper "The identification of the sodium-pump as the membrane-bound Na⁺/K⁺-ATPase: a commentary by Jens Chr. Skou" (Biochim. Biophys. Acta vol. 1000, pp. 435-438, 1989).

The work on ATPases initiated by professor Skou has been carried on at the Department of Physiology. Thus professor Torben Clausen works on the regulation of Na⁺,K⁺-transport and its clinical significance, Ca²⁺- and Mg²⁺-exchange in intact muscles, and associate professor Otto Hansen on isoforms of Na⁺,K⁺-ATPase and on the binding stoichiometry of specific ligands (nucleotide, ouabain, vanadate) to purified Na⁺,K⁺-ATPase and Ca²⁺-ATPase; associate professor Bente Vilsen studies the ion pump structure, regulation, and mechanism using enzyme kinetic measurements on site-directed mutants of Na⁺,K⁺-ATPase expressed in mammalian cells, and professor Jens Peter Andersen studies the ion pump structure, regulation, and mechanism using enzyme kinetic measurements on site-directed mutants of Ca²⁺-ATPase expressed in mammalian cells.

Other links:
University of Aarhus' link to:
The 1997 Nobel Prize in Chemistry
For further information on the Nobel Prize, see:
The Nobel Prize Internet Archive

Ole Sonne
Head of the Department of Physiology, University of Aarhus, Denmark

Revised 2003.01.15
Photos: Kirsten Kandborg
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