title: Conformational and biological properties of Bauhinia bauhinioides kallikrein inhibitor fragments with bradykinin-like activities.
abstract: Proteinase inhibitors extracted form medicinal plants are an interesting source of new drugs. Modifications in the structure of some of this kind of macromolecules could also lead to compounds of interesting biological properties. In this work, we synthesized and tested one fragment containing the reactive site of the Bauhinia bauhinioides kallikrein inhibitor (BbKI), denoted BbKI51-62 , and a related analog (P2 ) in which a proline residue was inserted in order to mimic the N-terminal region of the bradykinin molecule. The related retro-inverso counterparts Ri-BbKI51-62 and Ri-P2 were also included. The ability of these peptides to induce contraction of stomach fundus isolated from mouse was evaluated as well as their capability to induce calcium release from a cell culture of smooth muscle from guinea pig ileum. The conformational properties of the peptides were evaluated by circular dichroism and their resistance to enzymatic degradation by exposure to human blood plasma. Our results show that neither the parent BbKI51-62 nor its Ri-BbKI51-62 analog exhibit bradykinin-like activity, although the retro-inverso isomer was resistant to blood plasma degradation. On the other hand, the peptides P2 and Ri-P2 presented contractile activities on gastric smooth muscle from stomach fundus possibly by acting via B-2 receptor. Both compounds also induce calcium release from guinea pig ileum muscle cells in a manner similar to bradykinin. Moreover, both compounds also inhibited porcine pancreatic kallikrein. However, conformational analysis did not reveal any direct correlation between structure and biological effects.
authors.affiliation: Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, 04044-020, Brazil.
authors.forename: Flávio Lopes
authors.initials: FL
authors.lastname: Alves
authors.affiliation: Departamento de Bioquímica, Universidade Federal de São Paulo, São Paulo, SP, 04044-020, Brazil.
authors.forename: Maria Luiza Vilela
authors.initials: ML
authors.lastname: Oliva
authors.affiliation: Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, 04044-020, Brazil.
authors.forename: Antonio
authors.initials: A
authors.lastname: Miranda
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000031:analogs & derivatives*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004798:Enzymes / Q000097:blood; D006168:Guinea Pigs; D006801:Humans; D007082:Ileum / Q000166:cytology / Q000187:drug effects; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects*; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology*; D010940:Plant Proteins / Q000737:chemistry* / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry*; D017433:Protein Structure, Secondary; D059748:Proteolysis; D043782:Receptor, Bradykinin B2 / Q000378:metabolism; D013270:Stomach / Q000187:drug effects; D013552:Swine
chemical_list: C434623:BbKI protein, Bauhinia bauhinioides; D004798:Enzymes; D010455:Peptides; D010940:Plant Proteins; D043782:Receptor, Bradykinin B2; D001920:Bradykinin; D002118:Calcium
keywords: bradykinin; bradykinin-like activities; plant inhibitor; retro-inverso peptides