Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark.
A new sample preparation method for MALDI based on the use of a mixture of the two commonly used matrices, DHB and CHCA, is described. The matrix mixture preparation results in increased sequence coverage and spot-to-spot reproducibility for peptide mass mapping compared to the use of the single matrix components. This results in more reliable protein identification in proteomics studies and facilitates automated data acquisition. This method shows better tolerance towards salts and impurities, eliminating the need for pre-purification of the samples. It has also been found to be advantageous for the analysis of intact proteins, and especially for glycoproteins. The mixture allows the presence of rather high concentrations of urea in the sample solutions.