[en] The BPP7a heptapeptide, p-Glu1Asp2Gly3Pro4Ile5Pro6Pro7, forms an association complex with β-cyclodextrin in a 1:1 molar ratio. The peptide and its complex were characterized by circular dichroism (CD) and isothermal titration calorimetry (ITC), which showed a very weak interaction between the β-cyclodextrin and the peptide. Assignments of all hydrogen resonances of the peptide alone and as a complex were made using 1H nuclear magnetic resonance (NMR) experiments at 400 and 600 MHz. High resolution diffusion ordered spectroscopy (HR-DOSY) experiments were carried out to establish the self-aggregation state of BPP7a. It was also shown that the β-cyclodextrin breaks the molecular clusters leading to complex formation. In addition, the anti-hypertensive activity of the BPP7a/β-cyclodextrin complex was evaluated in spontaneous hypertensive rats (SHR), showing increased activity compared to that of pure BPP7a. (author)
Journal
[en] Herein, we demonstrate the physical and chemical characterizations of the supramolecular complex formed between β-cyclodextrin (βCD) and bradykinin potentiating nonapeptide (BPP9a), an endogenous toxin found in Bothrops jararaca. Circular dichroism results indicate a conformational change in the BPP9a secondary structure upon its complexation with βCD. Nuclear magnetic resonance results, mainly from NOESY experiments, and theoretical calculations showed a favorable interaction between the tryptophan residue of BPP9a and the βCD cavity. Thermodynamic inclusion parameters were investigated by isothermal titration calorimetry, demonstrating that βCD/BPP9a complex formation is an exothermic process that results in a reduction in entropy. Additionally, in vitro degradation study of BPP9a against trypsin (37 °C, pH 7.2) showed higher stability of peptide in presence of βCD. This βCD/BPP9a complex, which presents new chemical properties arising from the peptide inclusion process, may be useful as an antihypertensive drug in oral pharmaceutical formulations. Highlights: ► Cd and NMR showed evidences for the existence of more than one structure in solution. ► Complexation with βCD reduces the conformational rigidity of the peptide. ► βCD cavity recognize Trp and/or Pro segments of BPP9a. ► Interactions involving disaggregation of BPP9a assemblies and binding with βCD.
Journal
Materials Science and Engineering. C, Biomimetic Materials, Sensors and Systems; ISSN 0928-4931; 
; v. 32(2); p. 244-253
; v. 32(2); p. 244-253