Site specific labelling of proteins and peptides

The concept of this project is centred on carboxy-terminal sequencing of peptides and proteins using the isothiocyanate method, a method similar in concept to Edman degradation. All 20 natural amino acids have been shown to be able to be derivatised with isothiocyanate reagents such as diphenylphosphoryl isothiocyanate (DPP-ITC), which is one of the most studied derivatisation reagents. The terminal amino acid is derivatised to its thiohydantoin using a solid-supported isothiocyanate reagent, followed by cleavage from the peptide with a tag, thus leaving the peptide selectively labelled at its carboxy terminus. When this technique is then applied to a complex mixture of proteins, e.g. lysate of a cell, prior to 2D gel electrophoresis, it will allow improvement of detection of the difference in proteins which are up- or down-regulated after a cell has been treated with a drug. A successful outcome of this project will find applications in pharmaceutical and biomedical research and will enable a more efficient analysis of proteomes.