What are peptides and why are they important? This article seeks to demystify what peptides are and the role they play in everyday life and chemistry. Peptides are basically short chains of amino acids monomer that are chemically linked by amide bonds. Amide bonds are also widely denoted as peptide bonds, and both are often used interchangeably to refer to one another.
Peptides are can also be defined as compilations of natural amino acid structures that act as building blocks for enzymes and proteins. These peptides are folded and bonded to create a 3D structure, with the type of peptide formed during this process determining the type of protein produced. Each peptide form behaves differently with continued research revealing the full potential of all these important compounds. The formation of a peptide involves the elimination of one molecule of water from the condensation process of amino acids. This procedure often results in the formation of a peptide or amine bonds. The either ends of dipeptide molecule can also react to give rise to a tripeptide. This tripeptide in turn condenses with another amino acid, and this goes on and on. This process gives rise to the formations of long chains of amino acids. A good example if this is insulin that possesses 51 units of amino acids in two linked chains.
Peptides are so numerous and occur in plenty because of their ability to be synthesized or manufactured into very long chains. Though proteins and peptides are similar in structure, they have very noticeable and distinct differences between them. A protein, for instance, is a polymer of amino acids. It is a product of complex peptides containing several amino acids that are linked together. There are several known types of peptides. The ones with the shortest peptide chains are known as dipeptides. These dipeptides consist of two amino acids linked together by one peptide bond after the loss of the water molecule. The synthesis of peptide bonds has always required an input of free energy. Peptides bonds are very kinetically stable. Perhaps the most interesting and exciting fact about peptides is that in an aqueous solution a peptide bond in the absence a catalyst has a lifetime of close to a thousand years. Another type of peptides is tripeptide. The most essential and well-known example of this is glutathione. This compound is commonly found in significant concentrations in virtually all tissues. It contains glycine, glutamic acid and cysteine as its main ingredients. In tripeptides, the carboxyl acid lateral chain forms part of the backbone of the peptide structure quite different from the usual backbone that is often characteristic of a peptide, The normal carboxyl group is usually referred to as the side chain in this case.
A Polypeptide chain consists of a habitually repeating fragment. It acts as the main chain. In many instances, it is referred to as the backbone of these polypeptides and possesses a very high hydrogen bonding potential. Besides this chain, there is also a variable part. This is made up of unique and distinctive lateral or side chains. Every residue of the polypeptide chain consists of at least one member of the carbonyl group. This carbonyl group, as has been earlier discussed, has a high hydrogen-bond affinity except Proline, which serves as an excellent donor of the hydrogen bond. These two groups are highly reactive and effortlessly interact with each other. They also react with the functional groups present on these side chains. The reaction and integration are of great importance in stabilizing these polypeptide chains’ functional groups that are present on these side chains. Most of the naturally occurring polypeptide chains are made up of between 60 and 2000 amino acid residues. They are what is commonly referred to as proteins. When the polypeptide chains are small, they are called Oligopeptides or just peptides. Thorough Examination of the geometry of these polypeptides reveals a number of outstanding and previously unexplored characteristics. Some of these features are linked the characteristic of the basic peptides forming them. Peptides bond have been found to be mainly planar. They have also been found to contain a considerable double bond character preventing rotation about this bond. The inability of these bonds to rotate account for their planarity. Both the Trans and CIS configurations are possible for a normal peptide bond. More information on peptides can be found at Purity Peptide Labs and American Science Labs.