Using combinatorial techniques to synthesize a large number of compounds is very advantageous. It involves using the strategy of mix and split. This technique greatly increases the efficiency with, which the compounds are generated and reduces the reaction time.
Lysine is an aliphatic amino acid with an alpha-amino group, alpha-carboxylic group and a carbon side chain. Tyrosine is classified as an aromatic amino acid, which is derived by the process of hydroxylation at the para position of the phenylalanine.
Tyrosine sidechain, if unprotected, can get acylated during peptide- synthesis reactions. This leads to undesirable side-products and also, requires activated carboxylic acids to maintain complete coupling. It can also get attacked by cationic moieties released during the cleavage steps. Benzyl ether can be used to protect the tyrosine side chains from being cleaved or acylated.
Lysine side chains are very susceptible to repeated N-terminal deprotection cycles. This prevents the formation of the branched side-products, during the peptide synthesis. Lysine derivatives such as, allyloxycarbonyl and t-butyloxylcarbonyl are some of the commonly used lysine derivatives, used for side-chain protection.