| Grant number: | 12/12663-1 |
| Support Opportunities: | Research Projects - Thematic Grants |
| Start date: | December 01, 2012 |
| End date: | November 30, 2017 |
| Field of knowledge: | Biological Sciences - Biochemistry - Metabolism and Bioenergetics |
| Principal Investigator: | Paolo Di Mascio |
| Grantee: | Paolo Di Mascio |
| Host Institution: | Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
| City of the host institution: | São Paulo |
| Associated scholarship(s): | 15/13491-8 - Study of isotope labeling of Gluconacetobacter diazotrophicus by mass spectrometry (MALDI-TOF/TOF) and analysis of the morphology of vesicles by scanning electron microscopy, BP.IC |
Abstract
Aerobic metabolism and various toxicological and pharmacological reactions can generate "reactive" oxygen species capable of damaging biological molecules and triggering deleterious side effects. To counteract these effects, the cell is equipped with a set of enzymatic and chemical antioxidant defense lines. A balance between pro-oxidants and antioxidants constitutes the normal condition of aerobic life; an imbalance in favor of the pro-oxidants is termed "oxidative stress".Singlet molecular oxygen (1O2) has been shown to be generated in biological systems and have been implicated in cell defense mechanisms against viruses and bacteria. In addition to these effects, 1O2 can be responsible for ultraviolet A-induced activation of gene expression. Biological targets for 1O2 include unsaturated fatty acids, proteins, and DNA. However, unraveling the role of 1O2 in biological systems has been hampered by the difficulties to obtain 1O2 free from further reactive species. Our studies focus on providing the mechanism by which 1O2 and other reactive oxygen species play their physiological and pathological roles. We have been devoted to develop suitable 1O2 generators based on the thermolysis of endoperoxides. These compounds are chemically inert and have been employed as versatile sources of 1O2. Evidence has been accumulated during the last three decades on the strong implication of "reactive" oxygen species and one-electron oxidants in the generation of peroxides from several nucleobases, amino acids and unsaturated lipid components. Singlet oxygen is also a major source of peroxidation of several key cellular components. The breakdown products of the rather unstable peroxide (ROOH) as hydroperoxide precursors thus produced from exposure to endogenous or exogenous oxidizing agents may be implicated in deleterious biological effects such as cellular lethality, aging, mutagenesis and carcinogenesis. It may be added that oxidative processes to biomolecules are also involved in the etiology of other diseases including arteriosclerosis, arthritis, cataract and diabetes. The purpose of the present project is to extend our understanding of the reactions between reactive oxygen species, specifically 1O2 and ROOH with biomolecules in vitro and in vivo emphasizing the following aspects. Description of the main peroxidation reactions initiated by 1O2 and ROOH within key cellular targets including pyrimidine and purine nucleobases, several lipid components and amino acids. Studies on the molecular effects of the initial formation of the above peroxides within cellular components. Search of stable degradation products of biomolecules (ex. nucleobase) hydroperoxides that may be considered as the chemical signature of the formation of the latter unstable compounds that can be measured within cellular structure (ex. DNA, lipids, proteins). Major efforts have been devoted to the elucidation of the mechanisms of peroxidation of major cellular biomolecules including nucleic acids, lipids and proteins. Relevant peroxidation pathways are now available at least for the main components of the key cellular biomolecules although there is still a need of further studies, particularly for isolating and characterizing putative peroxides. Attempts should also be made to validate in the whole biomolecules the mechanisms of formation of peroxides that were inferred from model studies. Another relevant major topic deals with the search of molecular signature of the peroxide/1O2 formation in targeted biomolecules within cells upon exposure to oxidative conditions. It may be anticipated that gentle and sensitive mass spectrometric methods such as tandem mass spectrometry (MS/MS) in association with HPLC and the use of 18O-labeled peroxide/1O2 should constitute powerful tools for this purpose. (AU)
| Articles published in Agência FAPESP Newsletter about the research grant: |
| More itemsLess items |
| TITULO |
| Articles published in other media outlets ( ): |
| More itemsLess items |
| VEICULO: TITULO (DATA) |
| VEICULO: TITULO (DATA) |