Design, synthesis and characterization of modular peptide-based nanomaterials

Abstract

The term ‗amino acid‘ is generally understood to refer to the aminoalkanoic acids. They are compounds containing an amino group( NH2) and a carboxylic acid group (-COOH) with general formula H3N  (CR1R2)n COO n = 1 for the series of  amino acids, n = 2 for amino acids series and n = 3 for  amino acids series, etc.]. More than 700 amino acids have been discovered in nature and most of them are amino acids. Bacteria, fungi algae and plants are source for all these amino acids, which exist either in the free form or bound up into larger molecules (as constituents of peptides, proteins, other types of amide, alkylated and esterified structures). Among 700 amino acids twenty amino acids (actually, nineteen amino acids and one imino acid) that are utilised in living cells for protein synthesis under the control of genes are in a special category since they are fundamental to all life forms as building blocks of peptides and proteins. The structures of the 20 most common naturally occurring amino acids are shown in Table.1.1. All the amino acids except proline contain a primary amino group. Proline contains a secondary amino group incorporated in to a five-membered ring. The amino acids differ only in the substituent (R1 in general formula, R2=H) attached to the carbon. The wide variation in these substituents is what gives peptide and proteins their great structural diversity and is responsible for their great functional multiplicity. Eight kinds of side chains (R1= aliphatic chain, hydroxyl containing, sulphur containing, acidic, amides, basic, benzene containing and heterocyclic) are present in the most common natural amino acids, in that ten are essential amino acids (denoted by red asterisks (*) in Table