Abstract
Several approaches were investigated with the goal to obtain disulfide-free circularized analogues of the 58-residue small protein bovine pancreatic trypsin inhibitor (BPTI). These approaches include (1) a semisynthesis that uses as a starting point naturally occurring BPTI and takes advantage of the native proximity of the C- and N-termini; (2) a synthesis in which a peptide thioester prepared by stepwise Fmoc solid-phase chemistry is cyclized by a solution native chemical ligation step; (3) a stepwise Fmoc solid-phase synthesis of a protected circularly permuted linear sequence, followed by an attempted selective activation and head-to-tail cyclization; and (4) a stepwise Fmoc solid-phase synthesis of the same analogue, but using a different disconnection point, that features backbone amide linker (BAL) anchoring and attempted on-resin cyclization. The first two of these approaches were indeed successful in providing the desired target molecules in excellent purities and respectable yields, and could well be amenable to generalization. It is not yet clear whether or not the latter two approaches could be salvaged by modifications in the details of the chemical procedures applied.
Original language | English (US) |
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Pages (from-to) | 93-104 |
Number of pages | 12 |
Journal | International Journal of Peptide Research and Therapeutics |
Volume | 12 |
Issue number | 2 |
DOIs | |
State | Published - Jun 2006 |
Keywords
- Backbone amide linker (BAL)
- Bovine pancreatic trypsin inhibitor (BPTI)
- Circular proteins
- Native chemical ligation
- Peptide thioester
- Side-chain anchoring
- Solid-phase synthesis