| Grant number: | 11/17584-0 |
| Support Opportunities: | Regular Research Grants |
| Start date: | November 01, 2011 |
| End date: | October 31, 2013 |
| Field of knowledge: | Biological Sciences - Biochemistry - Chemistry of Macromolecules |
| Principal Investigator: | Antonio de Miranda |
| Grantee: | Antonio de Miranda |
| Host Institution: | Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil |
| Associated researchers: | Edgar Julian Paredes-Gamero ; Karin Do Amaral Riske ; Sirlei Daffre |
Abstract
Antibiotic resistance is a serious global public health problem with serious economic social and political implications, Given this reality, the search for new generations of antimicrobial substances is fundamental. Among the most promising therapeutic compounds studied are the antimicrobial peptides (AMPs). However, up to date, justa a few AMPs have been used clinically. Among the main problems of the use of AMPs are the high hemolytic and cytotoxic activity and instability in the plasma. The study of the structure / activity of this type of peptide may allow the development of most promising compounds from a therapeutic standpoint. For several years my group has been studying the characteristics of structures and antimicrobial activity of AMPs, especially the gomesin, which can dissociate the hemolytic activity of antimicrobial (Fazio et al. Biopolymers, 2007, 88 (3), 386-400). However, further analysis must be performed to better understand the mechanism of action of lytic Gm comparing it with other AMPs of similar structure, such as protegrina, and taquiplesina polifemusina. So if you seek to study the similarities and differences in the action of these peptides in terms of antimicrobial activity against bacteria and fungi, in lytic membrane mimetics (GUVs and Luvs) and cellular models. In the latter, mainly assess the general mechanisms of death triggered by different AMPs. As AMPs in general also have antitumor activity, we also intend to deepen the understanding of the biological action of gomesina in tumor cells. To this end, we will employ similar and marked with fluorescent probe with biotin to evaluate the differences in biological mechanisms of action in relation to the type of death and correlating it with the characteristics related to cytotoxicity, such as membrane binding, endocytosis and intra and extracellular stability. The peptides will be synthesized by solid phase method, will be purified by high performance liquid chromatography. The compounds will be characterized by liquid chromatography coupled to a mass spectrometer and amino acid analysis. The conformational studies will be carried out by Circular Dichroism. The interactions of vesicles with PAMS will be monitored by fluorescence spectroscopy, in addition to optical microscopy and isothermal titration calorimetry. The activities of antimicrobial peptides will be determined by a growth inhibition assay in liquid medium against microorganisms. The hemolytic activity and resistance to degradation in plasma will also be evaluated. The cytotoxicity, the mechanisms of cell death, and the stability of antimicrobial peptides will be evaluated by spectroscopic techniques, confocal microscopy, flow cytometry and electron microscopy. (AU)
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