Cholesterol, blondes and armadillos

Konrad Emil Bloch was born on 21 January 1912 into a prosperous Jewish family in Neisse, then in Upper Silesia, Germany. He studied chemistry in Munich and became particularly interested in the structure of natural products.

In 1934, Bloch left Germany under pressure from the Nazis and he spent two years investigating the phospholipids of tubercle bacilli at a sanatorium in Davos, Switzerland. Then, with help from contacts at Yale University, he emigrated to the US. He received his PhD at Columbia University in 1938 and taught there until 1946. During this period Bloch, in collaboration with David Rittenberg, began working on the biological synthesis of cholesterol, a subject that was to occupy his research interests for almost 20 years.

Bloch then moved to the University of Chicago, where he continued his work on cholesterol and the enzymatic synthesis of tripeptides. In 1954, he was appointed Higgins Professor of Biochemistry at Harvard University, a post he held until his retirement in 1982. In 1964 Bloch shared the Nobel prize in physiology or medicine with Feodor Lynen for discoveries concerning the mechanism and regulation of cholesterol and fatty acid metabolism.

In his retirement he wrote a popular science book, ‘Blondes in Venetian paintings, the nine-banded armadillo and other essays in biochemistry’, in which he mused on various aspects of biochemistry while explaining the chemical basis for biological phenomena.

Among the topics he covered were the multistep biosynthesis of cholesterol, how some important biochemical processes were discovered because of contamination, the importance of trial and error in research, lactose intolerance, why domestic cats need to hunt and the choice of animal models (including the nine-banded armadillo) in research.

He also wondered why artists such as Titian, Tintoretto and Veronese depicted dark-eyed blonde women many years before the discovery of hydrogen peroxide. He attributed the amber-tinted “biondezza” to exposure to bright sunlight combined with the application of “aqua bionda” — a mixture of plant material such as goosefoot (Chenopodium spp), which yields hydrogen peroxide via ascaridole-type endoperoxides, and madder (Rubia tinctorum) for the reddish-orange tint.

Bloch said that writing an autobiography did not appeal to him. But by sharing his thoughts on such diverse topics in this book he revealed more of his wide-ranging knowledge and personality than might have been conveyed by a conventional autobiography.