Charles H. Stammer

Dehydrophenylalanyl analogs of bradykinin: synthesis and biological activities.

Abstract We have synthesized three analogs of the potent vasodilator peptide bradykinin, ArgProProGlyPhe SerProPheArg (BK), containing dehydrophenylalanine (Δ z Phe) in place of the phenylalanyl residues at positions 5 and/or 8. The analogs, [Δ z Phe 5 ]BK, [Δ z Phe 8 ]BK, and [Δ z Phe 5,8 ]BK, were assayed for their effects on isolated smooth muscle tissues and on the systemic arterial blood pressure of rats. In these assays [Δ z Phe 5 ]BK showed considerably high biological activities, particularly in terms of its blood pressure-lowering effects, being over 23 times more potent than BK when given intravenously. [Δ z Phe 8 ]BK was less potent than BK and [Δ z Phe 5,8 ]BK had effects comparable to those of BK. All three synthetic analogs appear to be more resistant than BK to enzymic degradation during passage through the pulmonary vascular bed.

Trimethylsilyl iodide as a peptide deblocking agent

Removal of urethane and benzyl ether blocking groups from peptides is readily accomplished by treatment with trimethylsilyl iodide which is particularly useful for the debenzylation of O-benzyltyrosine without the formation of rearrangement products.

Use of a new protecting group in an attempted synthesis of cyclopropyldihydroxyphenylalanine

On introduit un groupe N-phtaloyl en condensant le benzaldehyde avec la N-(o-t-butoxycarbonylbenzoyl) glycine

Convenient synthesis of α-acylamino aldehydes

The reduction by di-isobutylaluminium hydride of N-blocked amino acid imidazolides gives good yields of α-acylamino aldehydes, the optical purity of which is higher than those previously reported, but a check of one aldehyde prepared showed only 60% optical purity; the chemical shifts at the aldehydo 13C and 1H resonances are reported.

Synthesis of 2,3-methano-glutamic and -pyroglutamic acid

2,3-Methano-analogues of glutamic and pyroglutamic acid have been synthesized and the β-naphthylamide of the latter is shown to be stable to pyroglutamic amino peptidase; the crystal structure of the methyl pyroglutamate analogue has been determined.

Configuration of dehydroleucine derivatives; X-ray crystal structure of N-Boc-Δα-leucine

Crystalline N-Boc-Δα-leucine (2), prepared by the N-chlorination procedure, has been subjected to single-crystal X-ray diffraction analysis; the double bond has the Z-configuration, while ϕ=–55, ψ= 162, and ω=–8°.