PEPTIDES AND PROTEINS - OVERVIEW AND STRATEGY

This chapter gives an overview and strategy for peptides and proteins. There are many problems in peptide and protein structure that can be simply solved by determining molecular weights to better than one mass unit. One of the first applications of fast atom bombardment- mass spectrometer (FAB-MS) to protein structure was the verification and, if necessary, correction of the DNA sequence of a gene coding for the corresponding protein. It merely requires translating the open reading frame of the gene sequence into the corresponding protein sequence and calculating the molecular weights of the tryptic peptides expected from the locations of lysine and arginine. Matching these values with the actual molecular weights, determined by FAB-MS, of the components of the tryptic digest of the protein reveals whether or not the DNA is correct. Those values that do not match indicate either an error in the DNA sequence or a posttranslational modification of the gene product. Sequence errors are usually misidentifications of a base that leads to a codon representing a different amino acid, or a deletion or insertion of a base causing a frame shift. © 1990, Elsevier Inc. All rights reserved.