ABSTRACT
A multimeric protein is a protein containing more than one folded polypeptide. Each of these folded polypeptides was originally synthesized by a ribosome from messenger RNA that encoded a sequence of amino acids of a precise, finite length. The only indubitably reliable method for determining the length and amino acid composition of a polypeptide, and consequently, its precise molar mass, is to sequence it correctly. Systems for stacking complexes between dodecyl sulfate and polypeptides have been developed to improve the resolution of the separation. Unfolded polypeptides and unfolded single-stranded nucleic acids are examples of well-defined extended polymers. A catalogue of the polypeptides from which a protein is formed is reliable only if the shortcomings of electrophoresis in the presence of dodecyl sulfate have been recognized and eliminated. The use of tryptic peptide mapping to provide evidence for the homogeneity of the polypeptides in a protein relies on the assumption that the trypsin has digested the polypeptide completely.
