Marceli Nencki was born in 1847 in Boczki near Sieradz in western Poland. He studied medicine in Berlin and obtained the degree of Doctor of Medicine in 1870 for his studies on the oxidation of aromatic compounds in animal body. In 1872 he was offered a position of research assistant at the University of Berne (Switzerland). In 1876 he was appointed Associate Professor and a year later full Professor and Director of the Institute of Medical Chemistry (Medizinisch-Chemisches Institut) at the University of Berne (presently Institut für Biochemie und Molekularbiologie). After 20 years in Berne, Nencki accepted in 1891 the invitation to organize, together with the well-known Russian physiologist Ivan P. Pavlov, the Institute of Experimental Medicine in Russia’s capital St. Petersburg where he spent the last decade of his life. He died of stomach cancer in 1901 at the age of 54.

Nencki’s scientific interests concentrated, among others, on urea synthesis, chemistry of purines and biological oxidation of aromatic compounds. He was also interested in the structure of proteins, enzymatic processes in the intestine and bacterial biochemistry. One of his important achievements was the demonstration that urea is formed from amino acids rather than being preformed on a protein molecule and that its biosynthesis is accompanied by carbon dioxide fixation. He also demonstrated, together with I.P. Pavlov, that liver is the site of urea synthesis in the animal body. Among Nencki’s greatest successes was his study on the chemical structure of haemoglobin, the red blood pigment (see below).

Three letters of Nencki to Marchlewski (recently acquired by the Institute) concerning their collaboration on haemoglobin and chlorophyll. Leon Marchlewski (1869-1946), who studied chemical nature of the green plant pigment chlorophyll, initially in the United Kingdom and then at the Jagiellonian University in Kraków (Poland), came across Nencki (who by then was interested in the chemical structure of the red blood pigment haemoglobin) by chance through professional literature. The two scientists started correspondence and exchanging samples of degradation products of their pigments. The ultimate result of this long-distance collaboration was the discovery of a close chemical relation between haem and chlorophyll.