1. Proteins: the molecular actors of life

Proteins are abundant in all organisms and, in fact, are essential constituents of life. They have a very wide range of functions. Perhaps one of the best known is their ability to catalyze chemical reactions: most chemical reactions that take place in a biological system are catalyzed by enzymes, which are proteins. Catalyzed reactions may involve very simple systems, such as the hydration of carbon dioxide, or chemical modifications of small organic molecules, or even complex transformations of macromolecules, or reactions involving mechanical work. Enzymes...