Emil Fischer. Photo provided by the Edgar Fahs Smith Collection, University of Pennsylvania Library. Emil Fischer (1852–1919) Emil Fischer might have gone into the family lumber business had his father had his way. But his father relented and allowed his son to study science after the young Emil proved himself unskilled in business. Early in his career Fischer discovered a family of bases called purines. Caffeine and theobromine, found in tea, coffee, and chocolate, are two familiar purines. Other purines, discovered later, are important building blocks of DNA. Fischer also studied sugars and determined their structures using a synthetic strategy. He would synthesize compounds with the molecular structure he suspected a particular sugar might have; if he obtained that sugar, he knew he was correct. Fischer also discovered D-L isomerism in sugars. His study of sugars led him to study the fermentation of sugars and the enzymes that cause it. And, enzymes being proteins, he then turned his attention to the nature of proteins in general. Fisher showed that proteins are made of chains of amino acids. For his work on sugars, he was awarded the 1902 Nobel Prize in chemistry. Fischer was married and had three sons, two of whom died during World War I. The loss was unbearable, and he took his own life in 1919.