Chemistry/peptides

Peptides are the family of molecules formed from the linking, in a defined order, of various of the amino acids. How do peptides differ from proteins, which are also long chains of amino acids; by virtue of their size. Traditionally, those peptide chains which are short enough to make synthetically from constituent amino acids are called peptides rather than proteins. The limit to how long a peptide may now be made is slowly increasing, but once a chain is beyond about 75 residues (that is, amino acids)it is becoming the realm of protein chemistry. So, the vast majority of peptides are 50 amino-acids or less in length, and naturally-ocurring proteins tend, at their smallest, to be measured in the hundreds of residues. Peptides occur in nature just like proteins, and are responsible for a bewildering array of functions, many of which are not yet understood.