ACS Chemistry for Life

Enzymes are complex compounds that make possible the chemical reactions of life. These complex molecular machines, almost all of which are proteins, work on a variety of other molecules, called substrates, to facilitate such changes as transfer of electrons (oxidation and reduction), molecular rearrangements, and water removal. Life goes on only because of the action of enzymes. The more scientists understand the workings of enzymes, the better they understand the complex array of reactions that make up the web of life, in healthy and in diseased states. Seminal work published in 1912 by Leonor Michaelis (1875–1949) and Maud Leonora Menten (1879–1960), a German man and a Canadian woman, cast light on the reasons why enzymes are so efficient.

Michaelis and Menten were able to express mathematically the relationship they were investigating, which demonstrated that each enzyme not only has its own substrate but also that at sufficient concentrations of substrate it has its own rate of causing that substrate to change chemically. One of the constants used in expressing this rate is now called the Michaelis-Menten constant. Much later, in the 1930s, their work was highlighted by J. B. S. Haldane, a British physiologist, biochemist, and geneticist. Michaelis went on to study how enzyme activity is inhibited, a topic later of great importance to the development of pharmaceuticals.

Visit Chemistry in History to learn more about Leonor Michaelis and Maud Leonora Menten.

Excerpted with permission, Chemical Heritage Foundation
www.chemheritage.org