Emerson Finco Marques
@iq.uso.br
Universidade de São Paulo
Research
EDUCATION
Doctor in science
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Sze M. Lo, Pierina A. Martinez, Emerson F. Marques, Sayuri Miyamoto, Glaucio Valdameri, Vivian R. Moure, Silvio M. Zanata, and Lia S. Nakao
Archives of Biochemistry and Biophysics Elsevier BV
Emerson Finco Marques, Marisa H.G. Medeiros, and Paolo Di Mascio
Wiley
Singlet molecular oxygen (1 O2 ) has been associated with a number of physiological processes. Despite the recognized importance of 1 O2 -mediated protein modifications, little is known about the role of this oxidant in cross-link formation and protein aggregation. Thus, using lysozyme as a model, the present study, sought to investigate the involvement of 1 O2 in cross-link formation. Lysozyme was photochemically oxidized in the presence of Rose Bengal or chemically oxidized using [18 O]-labeled 1 O2 released from thermolabile endoperoxides. It was concluded that both 1 O2 generating systems induce lysozyme crosslinking and aggregation. Using SDS-PAGE and nano-scale liquid chromatography coupled to electrospray ionization mass spectrometry the results clearly demonstrated that 1 O2 is directly involved in the formation of covalent cross-links involving the amino acids Histidine, lysine and Tryptophan.
Emerson Finco Marques, Marisa H.G. Medeiros, and Paolo Di Mascio
Wiley
Singlet molecular oxygen (1 O2 ) is generated in biological systems and reacts with different biomolecules. Proteins are a major target for 1 O2 , and His, Tyr, Met, Cys, and Trp are oxidized at physiological pH. In the present study, the modification of lysozyme protein by 1 O2 was investigated using mass spectrometry approaches. The experimental findings showed methionine, histidine, and tryptophan oxidation. The experiments were achieved using [18 O]-labeled 1 O2 released from thermolabile endoperoxides in association with nano-scale liquid chromatography coupled to electrospray ionization mass spectrometry. The structural characterization by nLC-MS/MS of the amino acids in the tryptic peptides of the proteins showed addition of [18 O]-labeling atoms in different amino acids.
Verônica Paviani, Raphael F. Queiroz, Emerson F. Marques, Paolo Di Mascio, and Ohara Augusto
Elsevier BV
Raphael F. Queiroz, Verônica Paviani, Fernando R. Coelho, Emerson F. Marques, Paolo Di Mascio, and Ohara Augusto
Portland Press Ltd.
Tempol (4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl) reduces tissue injury in animal models of various diseases via mechanisms that are not completely understood. Recently, we reported that high doses of tempol moderately increased survival in a rat model of ALS (amyotrophic lateral sclerosis) while decreasing the levels of oxidized hSOD1 (human Cu,Zn-superoxide dismutase) in spinal cord tissues. To better understand such a protective effect in vivo, we studied the effects of tempol on hSOD1 oxidation in vitro. The chosen oxidizing system was the bicarbonate-dependent peroxidase activity of hSOD1 that consumes H2O2 to produce carbonate radical, which oxidizes the enzyme. Most of the experiments were performed with 30 μM hSOD1, 25 mM bicarbonate, 1 mM H2O2, 0.1 mM DTPA (diethylenetriaminepenta-acetic acid) and 50 mM phosphate buffer at a final pH of 7.4. The results showed that tempol (5–75 μM) does not inhibit hSOD1 turnover, but decreases its resulting oxidation to carbonylated and covalently dimerized forms. Tempol acted by scavenging the carbonate radical produced and by recombining with hSOD1-derived radicals. As a result, tempol was consumed nearly stoichiometrically with hSOD1 monomers. MS analyses of turned-over hSOD1 and of a related peptide oxidized by the carbonate radical indicated the formation of a relatively unstable adduct between tempol and hSOD1-Trp32•. Tempol consumption by the bicarbonate-dependent peroxidase activity of hSOD1 may be one of the reasons why high doses of tempol were required to afford protection in an ALS rat model. Overall, the results of the present study confirm that tempol can protect against protein oxidation and the ensuing consequences.