A Novel Approach to Amino Acid Sequencing
This chapter develops a procedure for determining the arrangement of several different amino acids in a polypeptide chain. It provides important information for the undertaking of an amino acid sequence by more traditional routes. DNA sequencing was pioneered by Sanger, who used Polyacrylamide gels to separate populations of radioactive DNA fragments that were distinguished by the relative occurrences of the four bases; amazingly, the sequence could be read directly off the gel. When enzymes are used to cleave labeled proteins, care must be taken to unfold the protein so that each of the targeted sites has an equal opportunity for encounter. The preparation is then exposed to some fluorescent or radioactive reagent that reacts with amino groups, and a labeled product emerges that is ready for fragmentation and electrophoresis. The computer copies out each sequence for examination and deletes all residues except the ones of interest.