Synthetic study of phosphopeptides related to heat shock protein HSP27.

Two kinds of phosphoserine-containing peptides related to HSP27 were synthesized by the Boc- or Fmoc-mode solid-phase method based on prephosphorylation strategy. In the case of the Boc strategy, the O-phosphono group of the phosphoserine residue was protected with the cyclopentyl or cyclohexyl group. On the other hand, N'-Fmoc-O-[(benzyloxy)-hydroxyphosphinyl]serine was employed in case of the Fmoc strategy.

Missense mutation of amylin gene (S20G) in Japanese NIDDM patients.

Many studies suggest that amylin, which is cosecreted with insulin from islet beta-cells, is a biologically active peptide and modulates plasma glucose levels. We therefore scanned the amylin gene for mutations in 294 Japanese NIDDM patients by single-strand conformational polymorphism, and we found a single heterozygous missense mutation (Ser-->Gly at position 20: S20G mutation) in 12 NIDDM patients (frequency 4.1%).

Omega-agatoxin-TK containing D-serine at position 46, but not synthetic omega-[L-Ser46]agatoxin-TK, exerts blockade of P-type calcium channels in cerebellar Purkinje neurons.

omega-Agatoxin-TK (omega-Aga-TK), a 48-amino-acid peptide isolated from the venom of the funnel web spider (Agelenopsis aperta), is a selective and potent inhibitor of P-type calcium channels in the nervous system. We have synthesized a peptide that has the amino acid sequence identified for native omega-Aga-TK. The synthetic omega-Aga-TK, however, showed 80-90-fold less potent inhibition of P-type calcium channels, compared with native omega-Aga-TK.

Synthesis of omega-agatoxin IVA and its related peptides.

A potent and selective P type calcium channel blocker isolated from the venom of the funnel web spider Agelenopsis aperta, omega-agatoxin IVA, and its related peptides were synthesized by the solution procedure. Synthetic omega-agatoxin IVA was found to block high-threshold P-type calcium current in rat Purkinje neuron with the same potency as that reported for the natural product. Its disulfide structure was determined by amino acid analysis, gas-phase sequencing and mass spectrometry of the proteolytic fragments.

Suppression of a side reaction associated with N(im)-benzyloxymethyl group during synthesis of peptides containing cysteinyl residue at the N-terminus.

During the synthesis of His-containing peptide, having a Cys residue at the amino terminus, by the HF method, a large quantity of an unexpected product was formed when the His residue was protected by the benzyloxymethyl (BOM) group. This side product was found to be a thioprolyl-peptide which was formed from the Cys-peptide with formaldehyde released from the Bom group by HF. In order to suppress this side reaction, we tried using various scavengers and found that Cys and its derivatives were most effective, although they could not completely suppress the side reaction.