Proteins: An Introduction
Abstract
Protein are polymers made up of amino acids linked by peptide bonds. Twenty different amino acids are commonly found in proteins. Most proteins contain between 100 and 500 amino acids whose sequences are specified by the corresponding genes. A typical eukaryotic cell contains on the order of 10,000 proteins; the total number of proteins found in nature is much larger because of the existence of many mutant proteins and differences generated by evolution between homologous proteins in different species. Proteins fold spontaneously to form compact structures with complex surfaces built upon a framework of α-helices and pleated-sheets. Their ability to strongly and specifically interact with other molecules depends upon complementarity between binding sites on the surface of the folded protein, and the shapes and chemistries of the molecules to be bound. Proteins act as molecular machines, transforming or translocating the molecules with which they interact. Procedures for designing and producing novel proteins in the test tube are now being developed. © 1995, Elsevier B.V.