RESUMO
QK peptide is a vascular endothelial growth factor (VEGF)-mimetic molecule with significant proangiogenic activity. In particular, QK is able to bind and activate VEGF receptors (VEGFRs) to stimulate a functional response in endothelial cells. To characterize the peptide bioactivity and its molecular recognition properties, a detailed picture of the interaction between peptide QK and VEGF receptors is reported. By combining NMR spectroscopy studies in solution on the purified receptor and in the presence of intact endothelial cells, a molecular description of the binding interaction between peptide QK and VEGFR2 in the cellular context is obtained. These results reveal useful insights into the peptide biological mechanism, which opens the way to further optimization of this class of VEGF-mimicking peptides.
Assuntos
Materiais Biomiméticos/química , Peptídeos/química , Receptores de Fatores de Crescimento do Endotélio Vascular/química , Fator A de Crescimento do Endotélio Vascular/química , Células Endoteliais , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Ligação Proteica , Conformação ProteicaRESUMO
Molecular tools to stabilize the ß-hairpin conformation are needed as ß-hairpin peptides are useful molecules for pharmaceutical, biological and materials applications. We explored the use of a "triazole bridge", a covalent link between two ß-hairpin strands obtained through Cu-catalyzed alkyne-azide cycloaddition, combined with an aromatic-aromatic interaction. Highly conformationally stable peptides were identified by NMR screening of a small collection of cyclic peptides based on the Trpzip2 scaffold. The characteristic Trp-Trp interaction of Trpzip2 was replaced by a diagonal triazole bridge of variable length. NMR and CD analyses showed that triazole and indole rings could favorably interact to stabilize a ß-hairpin conformation. The conformational stabilization depends on the length of the triazole bridge and the reciprocal position between the aromatic rings. Combining aromatic interactions and the covalent inter-strand triazole bridge is a useful strategy to obtain peptides with a high ß-hairpin content.
Assuntos
Peptídeos/química , Triazóis/química , Triptofano/química , Sequência de Aminoácidos , Catálise , Cobre/química , Reação de Cicloadição , Peptídeos/síntese química , Peptídeos Cíclicos/síntese química , Peptídeos Cíclicos/química , Conformação Proteica em Folha beta , Estabilidade Proteica , Termodinâmica , Triazóis/síntese química , Triptofano/síntese químicaRESUMO
The ability to modulate angiogenesis by chemical tools has several important applications in different scientific fields. With the perspective of finding novel proangiogenic molecules, we searched peptide sequences with a chemical profile similar to that of the QK peptide, a well described VEGF mimetic peptide. We found that residues 1617-1627 of the IQGAP1 protein show molecular features similar to those of the QK peptide sequence. The IQGAP1-derived synthetic peptide was analyzed by NMR spectroscopy and its biological activity was characterized in endothelial cells. These studies showed that this IQGAP1-derived peptide has a biological activity similar to that of VEGF and could be considered as a novel tool for reparative angiogenesis.
Assuntos
Indutores da Angiogênese/farmacologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Peptídeos/farmacologia , Fator A de Crescimento do Endotélio Vascular/farmacologia , Proteínas Ativadoras de ras GTPase/química , Sequência de Aminoácidos , Indutores da Angiogênese/síntese química , Animais , Aorta/citologia , Aorta/efeitos dos fármacos , Aorta/metabolismo , Caspase 3/genética , Caspase 3/metabolismo , Linhagem Celular Transformada , Proliferação de Células/efeitos dos fármacos , Células Endoteliais/citologia , Células Endoteliais/metabolismo , Regulação da Expressão Gênica , Células Endoteliais da Veia Umbilical Humana/citologia , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Mimetismo Molecular , Neovascularização Fisiológica/efeitos dos fármacos , Peptídeos/síntese química , Conformação Proteica em alfa-Hélice , Suínos , Fator A de Crescimento do Endotélio Vascular/química , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/genética , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/metabolismo , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/genética , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
Vascular Endothelial Growth Factor mimetic peptides have interesting applications in therapeutic angiogenesis. Recently, we described the proangiogenic properties of a 15 mer peptide designed on the N-terminal helix 17-25 of VEGF. The peptide was stabilized introducing well known peptide chemical tools among which N- and C-terminal capping sequence. Here, we show that the C-terminal sequence does not affect the structural and biological properties of the full-length peptide. In fact, a C-terminal truncated analog peptide resulted in a well folded and stable helix retaining the ability to bind to VEGF receptors. This study will allow to develop smaller peptidomimetic analogs able to modulate the VEGF-dependent angiogenesis.
Assuntos
Materiais Biomiméticos/química , Neovascularização Patológica/metabolismo , Neovascularização Fisiológica/efeitos dos fármacos , Peptídeos/química , Fator A de Crescimento do Endotélio Vascular/química , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/química , Materiais Biomiméticos/farmacologia , Linhagem Celular Tumoral , Dicroísmo Circular , Humanos , Ressonância Magnética Nuclear Biomolecular , Peptídeos/farmacologia , Ligação Proteica , Estrutura Secundária de Proteína , Fator A de Crescimento do Endotélio Vascular/farmacologiaRESUMO
ß-Hairpin peptides were conformationally stabilized through a 1,4 disubstituted 1,2,3-triazole interstrand linkage. A NMR conformational analysis revealed that the ß-hairpin content depends on the number and position of substituent methylene units of the 1,2,3-triazole ring. These results will allow the design of metabolically stable peptidomimetic analogs of bioactive ß-hairpin peptides.
