CD-n.m.r. study of the solution conformation of bradykinin analogs containing α-aminoisobutyric acid |
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Authors: | JOHN R CANN ROBERT E LONDON CLIFFORD J UNKEFER RAYMOND J VAVREK JOHN M STEWART |
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Abstract: | The conformation in aqueous solution of several α-aminoisobutyric acid (AIB)-containing analogs of bradykinin (BK) has been probed by complementary CD and 1H n.m.r. measurements. The conclusion reached is that substitution of AIB for Pro2 and/or Pro3 in BK stabilizes a degree of β-turn conformation in the N-terminal tetrapeptide moiety of the resulting analogs. Changing the solvent from water to DMSO or TFE further enhances the contribution of particular hydrogen bonded structures to the time-averaged conformation of these peptides. Bradykinin and AIB7]-BK adopt similar hydrogen bonded conformations in TFE, apparently with a contribution from a β-turn involving their common Arg1-Pro2-Pro3-Gly4 moiety. The contrasting biological activities of BK and its AIB-analogs are considered in terms of the conformational analogy between the AIB-residue and cis1 Pro and the propensity for a β-turn at the N-terminus of the peptide. |
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Keywords: | α -aminoisobutyric acid β -turn bradykinin circular dichroism 1H n m r peptide conformation |
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