Protein Folding: Part I—Basic Principles

By the early 1900s proteins had been studied for more than a hundred years. Chemists had begun to extract proteins such as albumin and wheat gluten from animals and plants at the beginning of the previous century. The Dutch chemist Gerardus Johannes Mulder (1802–1880) had found that each one of these proteins had nearly the same composition. He thought that all were variations on a single primordial substance composed of carbon, nitrogen, hydrogen, and oxygen with variable amounts of sulfur and phosphorus. In 1838, the Swedish chemist Jons Jacob Berzelius (1779–1848) coined the name “protein” for this universal substance. These events were followed by groundbreaking investigations carried out in the later 1850s and 1860s by August Kekule (1829–1896) that helped lay the foundations for structural chemistry and protein science. In his studies, Kekule uncovered the tetravalent character of carbon, proposed its ability to bond to other carbons in long chains, and discovered the ring structure of benzene.