PEPTIDE-MAPPING BY CNBR DEGRADATION ON A NITROCELLULOSE MEMBRANE WITH ANALYSIS BY MATRIX-ASSISTED LASER-DESORPTION IONIZATION MASS-SPECTROMETRY

Nitrocellulose is examined as a membrane substrate for peptide mapping by CNBr digestion using MALDI MS analysis. Using this methodology, proteins electroblotted from SDS-PAGE can be purified on the membrane by washing and further characterized by in situ chemical digestion followed by MALDI MS analysis. It is demonstrated that nitrocellulose is versatile in such analysis due to its excellent retention of both small and large fragments and the wide range of fragments that appear in MALDI MS. This is particularly advantageous in cases where multiple reactions and washing steps are involved. The analysis is found to be improved by first eluting the digest from the membrane, since interaction of the matrix with nitrocellulose may degrade the MALDI MS performance.