Identification of human pituitary growth hormone variants by mass spectrometry.

The heterogeneity of human endogenous growth hormone (GH) is used in doping control analysis to distinguish it from the homogeneous recombinant analogue in plasma samples. Pituitary GH variants were characterized by gel electrophoresis and mass spectrometry. Besides 22 and 20 kDa isoforms, fragments of 9 and 12 kDa were identified and a glycosylated 23 kDa GH variant was elucidated to bear a HexHexNac 2 NeuAc modification presumably located at Thr 60.