Fragmentation of Proteins for Sequence Studies and Separation of Peptide Mixtures
When a protein has been judged homogeneous and the end groups and amino acid composition are known, the next step in the elucidation of the covalent structure is the degradation of the macromolecule into low molecular weight peptides which can be completely characterized with respect to composition and sequence. The entire composition of the protein should be accounted for by the summation of unique peptides. Once this is achieved, the sequenced peptides must be arranged in the same order as they occur in the intact protein. No single technique is ideally suited to accomplish this task; therefore, a combination of enzymic, or chemical and enzymic techniques, is required. The methods discussed in this chapter deal primarily with the fragmentation of proteins and the fractionation of the resulting peptide mixtures. With the exception of partial acid hydrolysis, the degradative procedures have been restricted to those which exhibit a reasonable degree of specificity and which are most often used to obtain sets of peptides necessary for the elucidation of the primary structure of a protein.
KeywordsCysteine Disulfide Lactone Oxytocin Asparagine
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