Axel Hugo Teodor Theorell (also known as Hugo Theorell) spent the majority of his career studying the action of oxidation enzymes, proteins essential for the metabolic process in plants and animals. His isolation of the yellow enzyme in the mid-1930s was a breakthrough toward a clearer understanding of the transformation in the cell of food into energy, called cellular respiration. Theorell's discoveries provided basic knowledge for the eventual creation of artificial life in the laboratory, and were essential to the study of such diseases as cancer and tuberculosis. In a related area of study, his work on the alcohol-burning enzymes led to a new method for testing the alcohol content in blood. He was the first to isolate myoglobin, a substance that gives certain muscles their red color. He also studied cytochrome c, a catalytic enzyme responsible for causing energy reactions in mitochondria, the cell's "powerhouse." Theorell...