Linear and cyclic peptide analogues of the polypeptide cardiac stimulant, anthopleurin-A. 1H-NMR and biological activity studies.

摘要: A loop corresponding to residues 8- 17 in the polypeptide cardiac stimulant anthopleurin-A is known be important for cardiostimulant activity of this molecule. To investigate and possible conformations isolation, two synthetic peptides have been studied. The first corresponds 6-20 with Cys6 replaced by Thr, second 6-21 anthopleurin-A, Thr21 Cys. introduction an additional cysteine latter peptide enabled intramolecular disulfide formed between N- C-terminal residues. Both linear disulfide-containing analogue lack Na+-channel binding parent molecule, indicating that although function other regions molecule must also involved activity. Assignments 'H-NMR spectra both are presented, their pH temperature dependences investigated. results show amide protons Gly5 Asnl 1 (corresponding GlylO Asnl6 anthopleurin-A) sample hydrogen-bonded solution. Based on these NMR data, non-random structure, encompassing 2 - 5 8 11, respectively, proposed, involvement such structures discussed.