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A detailed NMR, CD, fluorometry, and molecular modeling study of a novel bradykinin antagonist B-9340, containing a novel amino acid d-Igl (α-(2-indanyl)glycine) at position 7, was carried out. The sequence of B-9340 is d-Arg⁰-Arg¹-Pro²-Hyp³-Gly⁴-Thi⁵-Ser⁶-d-Igl⁷-Oic⁸-Arg⁹, where Hyp is hydroxyproline, Thi is β-(2-thienyl)alanine, and Oic is (3aS,7aS)-octahydroindole-2-carboxylic acid. The CD results exhibit a striking effect of SDS on the spectrum of the BK antagonist, indicating that interaction with the surfactant induces a folded peptide structure. The interaction of this antagonist with phosphatidylinositol was monitored by fluorometry, indicating that the interaction of the peptide with the lipid is cooperative, and gives a Hill coefficient of 2.3. The two-dimensional proton NMR measurements indicate that B-9340 has no stable secondary structure in water solution and contains about 10−15% cis peptide bonds arising from Pro², Hyp³, and Oic⁸. In SDS micelles, NMR reveals the existence of two β-turns based on a number of medium-range connectivities that were useful for molecular modeling. The actual molecular modeling and dynamic runs were performed on B-9340 in an environment consisting of a layer of octyl sulfate anions and water. The results indicate that the structure of B-9340 in a micellar environment is characterized by a nonideal βII-turn comprising residues Pro² to Thi⁵, a nonideal βII‘-turn comprising residues Ser⁶−Arg⁹, and broad folding in the middle part of the molecule. The structure is stabilized by several hydrogen bonds and by a salt bridge between the guanidine moiety of Arg¹ and the carboxyl group of Arg⁹, whereas the middle part of the peptide is buried in the micelle. The structure is deposited as Brookhaven PDB file 1 BDK.