BIOC 2010 Lecture Notes - Lecture 15: Edman Degradation, Serine Protease, N-Terminus
15 Mar 2016
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Document Summary
You have no information at all about what is in the test tube. Generating small chunks of protein that can be sequences. Sequencing machine can only do about 50 amino acids at a time. If you have an intact protein that is much longer than that, you only get some of the sequence. Get the complete sequence by chopping it into little bits. Use enzymes whose job it is to digest proteins and cleave peptide bonds: trypsin from the pancreas. Trypsin is good because it doesn"t completely digest the protein: it only cuts a peptide bond immediately downstream of lysine or arginine. Both of these amino acids are basic amino acids: positive charge at neutral ph. Cuts peptide bond on carboxyl terminal side of that amino acid. Next amino acid can be anything except proline. Peptide bond between carbonyl and amide nitrogen is digested in a hydrolysis reaction, resulting in a cut of the peptide bond.
