The versatility and efficiency of the N alpha-fluorenylmethoxycarbonyl method of solid-phase peptide synthesis have been further enhanced by recent and continuing refinements in side-chain protecting group, linker and amino acid-coupling technology. In contrast, comparatively little work has been carried out on studying and further improving the N alpha-deprotection step. This report demonstrates that, in low concentrations, the non-nucleophilic amidine 1,8-diazabicyclo[5.4.0]undec-7-ene is a preferred alternative to the more commonly employed piperidine for the rapid and efficient cleavage of the N alpha-fluorenylmethoxycarbonyl group in the continuous flow method of solid-phase peptide synthesis. In the cases studied, use of this base did not cause cyclization of Asp(OBut)-Gly or Asn-Gly sequence to succinimide derivatives. At the recommended concentration of 2% 1,8-diazabicyclo[5.4.0]undec-7-ene in dimethylformamide, racemization of resin-bound C-terminal S-trityl cysteine was substantially reduced compared with standard piperidine-mediated deprotection conditions. Additionally, use of the base appears to reduce the extent of broadening of ultraviolet fluorenylmethoxycarbonyl-deprotection peaks occasionally observed when piperidine is employed, indicating that its reaction kinetics and mode of action are different.

Amino Acid Sequence↗

PubMedDate not supplied

Solid phase peptide synthesis: recent advances and applications.

Techniques for the synthesis of peptides by solid phase procedures have advanced considerably over recent years and now enable the rapid and efficient preparation of complex and difficult sequences. These developments have led to many novel and unique applications of synthetic peptides which will find increasing and important utility in biotechnology.

Biotechnology↗

PubMedDate not supplied

Chemical synthesis of an O-phosphorylated tyrosine analogue of human angiotensin II, [Tyr(P)4] angiotensin II, and its vasoconstrictor effect in intact sheep.

The derivative N alpha-fluorenylmethoxy-carbonyl-O-dimethylphosphono-L-tyrosi ne was utilized in continuous-flow solid-phase synthesis to prepare the O-phosphotyrosine analogue of human angiotensin II, [Tyr(P)4] angiotensin II. Side-chain deprotection, including the removal of the methyl phosphate groups, as well as cleavage of the peptide from the solid support was achieved with 1 M trimethylsilyl-bromide-thioanisole in trifluoroacetic acid. Overall yield of purified peptide was 46%. The pressor response in intact sheep to graded infusions of the synthetic [Tyr(P)4] angiotensin II showed it to have similar potency to the native angiotensin II. However, a prolonged, elevated mean arterial pressure was observed following cessation of the infusion.

Amino Acid Sequence↗

PubMedDate not supplied

Solid phase synthesis and biological activity of rat relaxin.

The peptide hormone relaxin was isolated in good yield from the ovaries of the pregnant rodent Rattus rattus using a simplified purification schedule. It was subjected to comprehensive chemical characterization to confirm both its purity and predicted composition. The peptide was also chemically synthesized by the solid phase procedure. The two chains comprising the hormone were each assembled by the Boc-polystyrene method and, following conventional purification, combined in solution to form the single intramolecular and two intermolecular disulfide bonds. Following purification, the synthetic rat relaxin was fully chemically characterized and shown to be indistinguishable from the native peptide including by secondary structure analysis using circular dichroism spectroscopy. The native and synthetic rat relaxins were shown to be equally biologically active in the in vitro rat uterine relaxation assay and had pEC50 values that were comparable to synthetic human H2 relaxin.

Amino Acid Sequence↗