KLENK, ERNST

(b. Pfalzgrafenweiler, near Freudenstadt, Germany, 14 October 1869; d. Cologne, Federal Republic of Germany, 29 December 1971)

physiological chemistry

The son of Johannes Klenk, a brewer, and of Katharina Grossman, Klenk attended gymnasium at Tübingen, and after serving in World War I, he entered the University of Tübingen in 1918 to study chemistry. He took his doctorate in 1923 and worked under Hans Thierfelder, and later Franz Knoop, the discoverer of the β–oxidation of fatty acids. With Thierfelder he wrote a book on the chemistry of the cerebrosides (1930). In his early research under Knoop, Klenk worked on the oxidation of fatty acyl benzene derivatives, thereby laying the foundation for his interest in lipid and fatty acid chemistry. He became associate professor at Tübingen in 1931, and in 1936 he accepted the chair of physiological chemistry at Cologne, a position he held until his retirement in 1967. In 1931 Klenk married Margarete Aldinger, a physician; they had three sons.

Klenk made important contributions to lipid chemistry and more specifically to neurochemistry, a field that had been opened up by Johann Ludwig Wilhelm(John Louis William) Thudichum at the turn of the century. Thudichum summarized his lifework on the sphingolipids of the brain in his Die chemische Konstitution des Gehirns des Menschen und der Tiere (1901), Klenk did a considerable amount of work on the cerebrosides. He was the first to isolate nervon, cerebron, and other cerebrosides, and to describe in detail the structures of their fatty acid constituents. In 1929 he demonstrated for the first time the correct chain length (18C) of sphingosine; later he contributed to the elucidation of its structure. He also worked on the composition of polyenolic fatty acids, and he isolated a C₂₂ fatty acid that was more highly unsaturated than the wellknown arachidonic acid.

In 1935 Klenk discovered a new class of sphingolipids, the gangliosides. This result came from the investigation of the biochemistry of various neurolipodystrophies, including Niemann-Pick disease, and especially from the study of Tay-Sachs disease, otherwise known as amanrotic idiocy. The latter is a familiar disease of infancy, characterized by a progressive degeneration of nerve cells, eventuating in weakness of the muscles and paralysis. Klenk suggested the name ganglioside for the type of glycolipid isolated in this disease, in direct analogy to the already named cerebrosides, and because this kind of glycolipid accumulated in the ganglia cells of the brain in Tay-Sachs disease.

Whereas cerebrosides are localized in white matter, gangliosides were initially thought to be unique to the gray matter of the brain. Because of their high concentration in the gray matter, they were initially regarded as characteristic components of nerve cells. Although gangliosides may be said generally to possess greater complexity than most other sphingolipids, it is now known that they are not exclusively localized either in neurons or in the brain.

In 1941 Klenk isolated neuraminic acid, in the form of the crystallized methylglycoside, from brain gangliosides. Later, with other groups, he went on to elucidate the structure of several gangliosides. He described the acceptor function of neuraminic acid for myxoviruses of the mumps-influenza group and found that neuraminic acid is the determinant group of the MN blood group system.

In the last years of his life, Klenk’s major effort was directed to the further purification and elucidation of ganglioside structures. His life’s work acted as a strong stimulus to others interested in the structure of sphingolipids and their chemical and enzymatic synthesis and metabolism.

Klenk was a founding member of the editorial board of the Journal of Neurochemistry (1957), and served as president of the Deutsche Gesellschaft für Biologische Chemie. Among his honors were the Norman Medal of the Deutsche Gesellschaft für Fettwissenschaft in 1953, the Oil Chemist Award in 1958, the Heinrich Wieland Prize in 1964, the American Oil Chemists Society Award in 1965, the Stouffer Prize in 1966, and the Otto Warburg Medal of the Deutsche Gesellschaft für Biologische Chemie in 1971.

BIBLIOGRAPHY

1.Original Works. A bibiography of Klenk’s scientific papers is in J. C. Poggendorff, Biographisch-literarisches Handwörterbuch der exakten Naturwissenschaften, VI, 1333, and VIIa, pt. 2. 781–872. His writings include Die Chemie der Cerebroside und Phosphatide (Berlin, 1930), with Hans Thierfelder; and “On the Discovery and Chemistry of Neuraminic Acid and Gangliosides,” in Journal of the Chemistry and Physics of Lipids, 5 (1970), 193–197.

11. Secondary Literature. Hildegard Debuch, “Ernst Klenk, 1896–1971,” in Journal of Neurochemistry. 21 (1973), 725–727.

Neil Morgan