Characterization of Photochemically Cross-linked Protein-nucleic Acid Complexes by Mass Spectrometry

Download or read book Characterization of Photochemically Cross-linked Protein-nucleic Acid Complexes by Mass Spectrometry written by Ole Nørregaard Jensen and published by . This book was released on 1994 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: A novel protocol for the study of protein-nucleic acid interactions is presented and demonstrated to be feasible. The protocol combines photochemical crosslinking techniques and mass spectrometric methods into a new strategy for identifying protein domains or amino acid residues that are in close contact with nucleic acid in protein-nucleic acid complexes. Identifying nucleic acid binding domains in proteins provides a starting point for understanding structure-function relationships in protein-nucleic acid complexes. The protocol can be divided into three parts: 1) Cross linking of the protein-nucleic acid complex by irradiation with ultraviolet light and subsequently verifying the crosslinking by mass spectrometry; 2) Mass spectrometric peptide mapping of crosslinked protein-nucleic acid complexes to identify crosslinked peptide-nucleic acid hybrids; 3) Tandem mass spectrometric sequencing of peptide-nucleic acid hybrids to localize the crosslinked amino acid residue(s). The experimental data described in this dissertation documents our efforts to establish and implement this analytical protocol. Using several different protein-nucleic acid systems and different crosslinking techniques, we have demonstrated the feasibility of a mass spectrometric based approach to structurally characterize UV-crosslinked protein-nucleic acid complexes. Matrix-assisted laser desorption/ionization mass spectrometry was for the first time demonstrated to be highly effective for detection and molecular weight determination of intact, UV-crosslinked protein-nucleic acid complexes and for molecular weight determination of synthetic and UV-crosslinked peptide-nucleic acid hybrids. Electrospray ionization mass spectrometry and tandem mass spectrometry was demonstrated to be effective for analysis of synthetic peptide-nucleic acid hybrids and, in conjunction with HPLC, for peptide mapping of a protein. The first application of MALDI mass spectrometry to the characterization of crosslinked peptide-nucleic acid hybrids isolated from a photochemically crosslinked protein-nucleic acid complex demonstrate that the new protocol can be used to identify nucleic acid binding domains in proteins.