Two-dimensional gel electrophoresis/matrix-assisted laser desorption/ionisation mass spectrometry of commercial bovine milk

Proteins in commercial bovine milk have been separated by two-dimensional g el electrophoresis and examined by matrix-assisted laser desorption/ionisal ion mass spectrometry. Gel separation was conducted in two different pH gra dients, 3-10 and 6-11; the latter range resulted in a higher spot resolutio n and favoured the basic proteins. We have limited the time-of-flight mass spectrometry analysis to the linear mode to examine the capability of relia ble relative molecular masses of the intact proteins in their characterisat ion. The present study draws attention to the difficulty of identifying bas ic proteins with low molecular masses (below 12000 Da) that are commonly en countered in milk samples. Copyright (C) 2001 John Wiley & Sons, Ltd.