Kuhne, Wilhelme (1837–1900)

German physiologist who coined the term enzyme (a substance produced by cells that is capable of speeding up chemical reactions) and was the first to show the reversible effect of light on the retina of the eye.

He began his research on substances responsible for the breakdown of foodstuffs in the digestive system. After working on the active substances in pancreatic juices, Kuhne coined the term enzyme, which he derived from the Greek words en which means ‘in’ and zyme which means ‘leaven’.

A mammalian cell has thousands of different enzymes which catalyse (trigger) essential chemical reactions to meet the requirements of the cell for growth, reproduction, synthesis, and breakdown of the products of metabolism. Enzymes enhance the rate of chemical reactions frequently by as much as a million-fold and are highly specific for the reactions they catalyse.

Kuhne was born in Hamburg and as a medical student was fortunate to work with the eminent physiologists Rudolf Virchow and Claude Bernard. In 1871 he became professor of physiology at the University of Freiberg.

He also worked on the photosensitive proteins present in the retina of the frog's eye and was the first to show the reversible effect of light on the activity of a coloured pigment (later called rhodopsin) in the retina.