Investigating the reaction of a novel silica capillary coating compound with proteins/peptides by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry

Quaternized piperazine ((N-methyl-N-omega -iodobutyl-N'-methyl)piperazine; QPzl) is a novel compound described as an ideal coating material for the si lica capillaries that are commonly used for capillary zone electrophoresis. In the course of such analysis, contact between such coatings and biomolec ules may result in certain modifications of the latter. To gain specific in formation on such potential modifications, solutions at pH 10.0 containing both QPzl and standard proteins/peptides were incubated for various periods and examined by matrix-assisted laser desorption/ionisation mass spectrome try. The reduction of the S-S bridges, denaturation in 8 M urea, the isoele ctric point of the protein and the duration of the incubation had a profoun d influence on the investigated reaction. Analysis in reflectron mode and p ost source decay identified Cys as the likely site of interaction. The impl ications of the present measurements for proteome analysis using capillary and gel electrophoresis are discussed. Copyright (C) 2001 John Wiley & Sons , Ltd.