Introduction: "Studies" Szeged
by Andrew G. Szent-Györgyi
August 13, 2005
Progress in science depends on seminal discoveries. These are findings that alter the approach of the field and generate a new framework for our thinking and experimental designs. The implications are frequently unexpected and not necessarily immediately recognized, for it is not easy to change one’s ideas and prejudices regarding how nature operates. Such was the case for a magical period encompassing three years experimentation performed in Szeged in Albert Szent-Györgyi’s laboratory. This work opened up an entirely new approach in our thinking of how muscle contraction operates. It became the foundation of muscle biochemistry and was pivotal for the development of the sliding filament theory and to our present understanding of the cross-bridge cycle.
The work was performed in complete isolation during the years of 1941 and 1943. By that time, Hungary had entered the war against the Allies; scientific papers published in the West, including even Nature and Science, were not available. Conversely, the results obtained in Szeged remained unknown to scientists in the western world. Szent-Györgyi recognized very early the evil nature of the Nazi empire. As early as 1933 he advised Hans Krebs to leave Germany for England. Szent-Györgyi fought against anti-Semitism, and did everything possible to prevent Hungary’s association with the axis powers. He had refused to submit his work during the war to German Journals. Arrangements were made with S. Karger Basel, New York, for publishing the results. Volume 1 of the papers was printed in Budapest, Volumes 2 and 3 in Szeged as “Studies from the Institute of Medical Chemistry University Szeged”. However, the war evidently prevented the publications from appearing abroad, and the results of the work became known only after the war. Just a few copies of the “Studies” were printed. These remained in Hungary, and the papers describing the experiments remained unavailable to western scientists.
Szent-Györgyi was famous in Hungary. He was the only Hungarian scientist who was awarded the Nobel Prize for work performed in Hungary. His hatred of the Nazis was well known. In 1943 a group who resisted German influence and Hungary’s participation in the war persuaded him to meet with the British authorities asking for separate peace. This was done under the guise of giving lectures in Istanbul with the knowledge and approval of the then Prime Minister, Miklós Kállay. Unfortunately, though he was able to contact the British, his mission became known to the Germans. Hitler personally demanded Szent-Györgyi’s extradition to Germany, which was refused by the Governor, Miklós Horthy. In March 19 the German Army occupied Hungary and Szent-Györgyi was placed under house arrest in Szeged. He had to obtain permission from the Gestapo to visit Budapest. On one such an occasion the Gestapo planned to arrest him at the railroad station. As luck had it, his son-in-law visited him and offered Szent-Györgyi a ride in his car to Budapest. There he went into hiding. He was convinced that he would not survive the war, and summarized his work in Szeged. This was published under the title “”Studies on muscle” in Acta Physiologica Scandinavica 9, Suppl. 25, 1945 and later in “Chemistry of Muscular Contraction” New York, Acad. Press Inc. 1951.
The main instruments of the laboratory in the Institute of Medical Chemistry consisted of Ostwald viscosimeters, a Pulfrich spectrophotometer, polarizing filters to observe flow birefringence, and two large centrifuges which had an upper limit of about 3000 revolutions per minute. With this simple assembly of instruments three fundamental discoveries were made. First, that the muscle protein “myosin” was a mixture of proteins. Banga and Szent-Györgyi observed that the properties of “myosin” depended on the extraction time of muscle with high salt. Long extraction produced a highly viscous protein; its viscosity was reduced by ATP. Short extraction yielded a protein of much lower viscosity which was unaffected by ATP. For this protein the name myosin was retained. Secondly, Straub was able to extract and isolate a second protein which was named actin. This protein formed a complex with myosin, which was highly viscous, but only in the absence of ATP. The complex was named actomyosin 1. The preparation of actin and its characterization by Straub was a remarkable achievement. He recognized that actin exists in two forms, a globular (G-actin) and a fibrous form (F-actin). Since polymerization takes place at increased ionic strength as well as at slightly acidic pH, of the protein was extracted in CO 2-free distilled water. To achieve this, myosin had to be destroyed by acetone to yield globular actin. It is noteworthy that the preparation of actin even now is essentially a modification of Straub’s procedure. Eventually actin turned out to be one of the most important proteins of the cell for maintaining cellular shape and movement. At the same time, Szent-Györgyi was able to purify actin-free myosin that formed paracrystals at low ionic strength. His method of purification of muscle myosin is also used even today. Thirdly; Szent-Györgyi found that threads made of actomyosin contracted in the presence of ATP, while threads prepared from myosin did not, i.e. contraction required the interaction of two proteins, myosin and actin 2.
These papers are exciting to read and are remarkable for their insight and directness. Their republication is not only valuable for historians but for students, old and young, interested in everything that moves. The editors deserve our thanks for making this possible.
Footnotes
1 The effect of ATP on the viscosity of “myosin” (probably actomyosin) was also discovered independently by Needham et al. in Cambridge. [Needham, J., S.C. Shen, D.M. Needham and A.S.C. Lawrence (1941) Nature 147:767-768]. They interpreted the results as a change in asymmetry of the molecule or the micellae formed by the molecules. The war prevented communication between the Szeged and the Cambridge groups until 1945 when J. Needham and Szent-Györgyi met in Moscow at the 225th anniversary celebrations of the U.S.S.R. Academy of Science.
2 It is noteworthy that there was considerable opposition to the proposal that contraction is the result of interaction of two proteins with ATP. The Nobel laurates, Cori and also Meyerhof did not believe that a molecule as large as myosin could be an enzyme as had been demonstrated earlier by Engelhardt and Ljubimova and made great and unsuccessful efforts to separate ATPase activity from myosin. The in vitro demonstration of contraction was not accepted by scientists of such stature as A.V. Hill, Astbury and Meyerhof; only after Szent-Györgyi showed in 1948 that glycerol extracted fiber bundles from psoas muscle could develop similar tensions as intact muscle did the finding gain general acceptance.. The preparation with some modification is still being used.