Introduction

Abstract

This introductory chapter provides an overview of proteins, which are a family of biological macromolecules that provide a variety of three-dimensional structures exquisitely shaped for their many different individual functions. They include structural proteins, enzymes, antibodies, regulatory proteins, sensors, transporters and pumps, and transducers. The common features of the chemical structures of proteins make possible a common synthetic mechanism: ribosomes assemble the great variety of proteins under the direction of different messenger RNA (mRNA) sequences. Both the DNA sequences of genes and the amino acid sequences of proteins are one-dimensional. The chapter asks: how then do proteins achieve their three-dimensional biologically active states? The three-dimensional structures of proteins are inherent in their amino acid sequences. It is the combination of a common synthetic machinery — the gene sequence dictating the amino acid sequence — with spontaneous folding to the native three-dimensional structure, that underlies the mechanism of molecular evolution.