Discrimination of mammalian growth hormones by peptide-mass mapping

Recognition by the legal authorities that growth hormones (GHs) may be abused to improve sporting performance and/or physique has led to the implementation of controls that make it an offence to produce, supply, possess or import and export GHs, with intent to supply, without the authority to do so. A method is described for the discriminatory analysis of human, equine, porcine and bovine GHs for forensic purposes. Peptide-mass mapping by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry following tryptic digestion gave sequence coverages of 97.4%, 93.7%, 94.2% and 90.6% for human, equine, porcine and bovine GHs respectively. The tryptic-mass maps generated were sufficient to discriminate between the four hormones analysed and thus provide unambiguous identification of each individual GH. Identification of the N-terminal peptides of recombinant equine and porcine GHs, which possess additional methionine residues, within the tryptic-mass maps may provide the basis of a test to indicate exogeneous administration rather than endogenous secretion of GH in performance dogs and horses.