Leonor Michaelis was born in Berlin in 1875 and received his MD in 1896 from the University of Berlin. After his medical degree he studied with German bacteriologist Paul Ehrlich. From 1899 to 1922 he was on the staff of Berlin Municipal Hospital, serving as director of it’s laboratories from 1906 to 1922. It was during this time he collaborated with Maud L. Menten. Together in 1913 they developed a rate law, called the Michaelis-Menten Equation that gave the dependence of the rate of substrate consumption –rS on the concentration of substrate, CS.
Km is called the Michaelis constant.
From 1929 until his retirement in 1940, Michaelis was a member of the Rockefeller Institute for Medical Research in New York. Michaelis died in 1949.