N-terminal Protecting Groups
Amino acids are added to excess to ensure complete coupling during each synthesis step, and without N-terminal protection, polymerization of unprotected amino acids could occur, resulting in low peptide yield or synthesis failure. N-terminal protection requires an additional step of removing the protecting group, termed deprotection, prior to the coupling step, creating a repeating design flow as follows:
- Protecting group is removed from the trailing amino acids in a deprotection reaction
- Deprotection reagents are washed away to provide a clean coupling environment
- Protected amino acids dissolved in a solvent such as dimethylformamide (DMF) combined with coupling reagents are pumped through the synthesis column
- Coupling reagents are washed away to provide clean deprotection environment
Currently, two protecting groups (t-Boc, Fmoc) are commonly used in solid-phase peptide synthesis. Their lability is caused by the carbamate group which readily releases CO2 for an irreversible decoupling step.
Read more about this topic: Peptide Synthesis, Protecting Groups
Famous quotes containing the words protecting and/or groups:
“The duty of government is to leave commerce to its own capital and credit as well as all other branches of business, protecting all in their legal pursuits, granting exclusive privileges to none.”
—Andrew Jackson (1767–1845)
“In America every woman has her set of girl-friends; some are cousins, the rest are gained at school. These form a permanent committee who sit on each other’s affairs, who “come out” together, marry and divorce together, and who end as those groups of bustling, heartless well-informed club-women who govern society. Against them the Couple of Ehepaar is helpless and Man in their eyes but a biological interlude.”
—Cyril Connolly (1903–1974)