The Edman Degradation Reaction
The peptide to be sequenced is adsorbed onto a solid surface - one common substrate is glass fibre coated with polybrene, a cationic polymer. The Edman reagent, phenylisothiocyanate (PITC), is added to the adsorbed peptide, together with a mildly basic buffer solution of 12% trimethylamine. This reacts with the amine group of the N-terminal amino acid.
The terminal amino acid can then be selectively detached by the addition of anhydrous acid. The derivative then isomerises to give a substituted phenylthiohydantoin which can be washed off and identified by chromatography, and the cycle can be repeated. The efficiency of each step is about 98%, which allows about 50 amino acids to be reliably determined.
Read more about this topic: Protein Sequencing
Famous quotes containing the words degradation and/or reaction:
“We found nothing grand in the history of the Jews nor in the morals inculcated in the Pentateuch.... I know of no other books that so fully teach the subjection and degradation of woman.”
—Elizabeth Cady Stanton (1815–1902)
“Children, randomly at first, hit upon something sooner or later that is their mother’s and/or father’s Achilles’ heel, a kind of behavior that especially upsets, offends, irritates or embarrasses them. One parent dislikes name-calling, another teasing...another bathroom jokes. For the parents, this behavior my have ties back to their childhood, many have been something not allowed, forbidden, and when it appears in the child, it causes high-voltage reaction in the parent.”
—Ellen Galinsky (20th century)