Detection of transthyretin variants using immunoprecipitation and matrix-assisted laser desorption/ionization bioreactive probes: A clinical application of mass spectrometry

In our continuing efforts to develop mass spectrometry-based methods for tr ansthyretin (TTR) variant detection and characterization, we have sought to use matrix-assisted laser desorption/ionization (MALDI) bioreactive probes incorporating immobilized trypsin for screening purposes. These devices sh ow good diagnostic potential as a clinical screening tool to detect amino a cid substitutions in TTR MALDI probes allow the on-probe generation of tryp tic digests. The subsequent mass analysis of the on-probe digest yields the peptide map. The inherent advantages of this method include considerably r educed digestion times (minutes vs. hours), absence of autolysis products, minimized sample handling, and hence minimal sample loss. A further advanta ge is that the opportunity for loss of hydrophobic peptides is reduced beca use no sample transfer occurs. The method can be applied as a preliminary s creen for TTR variants where TTR is isolated from patient serum through imm unoprecipitation. This method should also be applicable to other proteins a nd suitable for automation. (C) 2000 American Society for Mass Spectrometry .