As soon as proteins were discovered, investigators studied their role in disease. Prosper Sylvain Denis (1799–1863) wrote Études Chimiques, Physiologiques, et Médicales, Faites de 1835 à 1840, sur les Matières Albumineuses (1842) (Chemical, Physiological and Medical Studies, done from 1835 to 1840, on the Albuminous Materials). Chapter 9 (p. 141) is entitled “On the chemical modifications in albuminous materials of organic solids andfluids in the sick person.” He wrote (see arrow 1): “In effect, the disorders that so often torment the economy, frequently manifest themselves in these materials.” This passage includes a reference to caseine (“caséine”) and concludes (arrow 2) “Such knowledge already acquired proves that we will come to discover, one day, all the chemical modifications that illnesses carry in the albuminous materials.” The lower panel (from p. 144) shows a table comparing the water, proteins, alkali, and salts from healthy and diseased serum.
Life is a relationship between molecules, not a property of any one molecule. So is therefore disease, which endangers life. While there are molecular diseases, there are no diseased molecules. At the level of the molecules we find only variations in structure and physicochemical properties. Likewise, at that level ...