Application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for monitoring the digestion of phosphatidylcholine by pancreatic phospholipase A(2).

Analytical biochemistry

PubMedID: 12234464

Petkovic M, Müller J, Müller M, Schiller J, Arnold K, Arnhold J. Application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for monitoring the digestion of phosphatidylcholine by pancreatic phospholipase A(2). Anal Biochem. 2002;308(1):61-70.
Different methods were established for monitoring the phospholipase A(2)(PLA(2)) activity but all of them are rather cumbersome and time consuming. In this paper we have investigated the suitability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the determination of the PLA(2) activity. Phosphatidylcholine (PC) was digested with pancreatic PLA(2) under different conditions, i.e., various Ca(2+), PC, and PLA(2) concentrations. The digestion products were analyzed by MALDI-TOF MS and the concentration of lysophosphatidylcholine (LPC)-generated upon PLA(2) digestion-was determined by the application of an internal standard (known concentration) and by a comparison of their signal-to-noise ratios. The results clearly demonstrate that the LPC concentration determined from the MALDI-TOF mass spectra correlates directly with the activity of the applied enzyme. Additionally, LPC concentration increased with an increase in Ca(2+), as well as in the PC concentration. A single MALDI-TOF mass spectrum provides immediate information on the digestion products as well as on the residual substrate without requirements for any previous derivatization. MALDI-TOF MS can be easily and simply applied for monitoring the PLA(2) activity and we assume that this method might also be useful for other types of phospholipases.