Characteristics of the amino acids as components of a peptide hormone sequence

Abstract

In the living organism the polypeptide chains of proteins are used for the most diverse purposes: structural support and protection, catalysis of a wide range of chemical reactions, energy transduction, food storage, transport, and—among many others—regulation and co-ordination by information transfer (including humoral transmission by hormones). Molecules with the varied properties required for these multifarious functions are built up of a mere 20 units: the protein-constituent amino acids, connected primarily in a single structural mode (a linear sequence) but finally arranged in space in intricate ways to molecules of the required size, shape and properties. Although the peptide hormones fulfil such a highly specialised role, there is nothing to distinguish, a priori, their sequences from other polypeptide or protein sequences with different biological functions, or no function at all.