Linus Pauling in 1987.		Proteins and disease In 1949 Linus Carl Pauling (1901–1994) showed that a protein defect was the cause of sickle-cell anemia. Proteins are long, chainlike molecules made by joining together a precise sequence of many small molecules called amino acids. In 1956 the nature of the protein defect responsible for sickle-cell anemia was shown by Vernon Ingram to be a change in a single amino acid in the protein hemoglobin. This was the first time a molecular cause for any disease had been discovered and was a pinnacle in our understanding of proteins. The groundwork for this discovery had been laid by scientists like Emil Fischer (1852–1919), who showed that proteins were made of amino acids in 1907; Leonor Michaelis (1875–1949) and Maud Leonora Menten (1879–1960), who determined the kinetics of enzyme catalysis in 1913; and James Batcheller Sumner (1887–1955) and John Howard Northrop (1891–1987), who showed that enzymes are proteins in the 1920s and 1930s.