A5069359089- Hemoglobin structure and function
- Photosynthetic Processes and Mechanisms
- Photoreceptor and optogenetics research
- Electrochemical sensors and biosensors
- Nitric Oxide and Endothelin Effects
- Mass Spectrometry Techniques and Applications
- Metal-Catalyzed Oxygenation Mechanisms
- Electrochemical Analysis and Applications
- Porphyrin Metabolism and Disorders
- Electron Spin Resonance Studies
- Polysaccharides Composition and Applications
- Microbial Fuel Cells and Bioremediation
- Mitochondrial Function and Pathology
- Neonatal Health and Biochemistry
- Ammonia Synthesis and Nitrogen Reduction
- Phytochemicals and Antioxidant Activities
- Microbial bioremediation and biosurfactants
- Heme Oxygenase-1 and Carbon Monoxide
- Molecular Sensors and Ion Detection
- Enzyme Structure and Function
- Food composition and properties
- Microbial Applications in Construction Materials
- Marine Toxins and Detection Methods
- Polysaccharides and Plant Cell Walls
- Porphyrin and Phthalocyanine Chemistry
University of Cyprus
2013-2024
University of Nicosia
2014
University of Crete
1999-2009
University at Albany, State University of New York
2009
Institut de Biologie et Technologies
2009
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2009
CEA Paris-Saclay
2009
Centre National de la Recherche Scientifique
2009
Kyushu University
2009
Okazaki Institute for Integrative Bioscience
2005-2006
Extracts derived from the Ceratonia siliqua L. (carob) tree have been widely studied for their ability to prevent many diseases mainly due presence of polyphenolic compounds. In this study, we explored, first time, anti-cancer properties Cypriot carobs. We produced extracts ripe and unripe whole carobs, pulp seeds using solvents with different polarities. measured inhibit proliferation induce apoptosis in cancer normal immortalized breast cells, MTT assay, cell cycle analysis Western...
We have applied resonance Raman spectroscopy to investigate the properties of dinuclear center oxidized, reduced, and NO-bound nitric-oxide reductase from <i>Paracoccus denitrificans</i>. The spectra oxidized enzyme show two distinct ν<sub>as</sub>(Fe-O-Fe) modes at 815 833 cm<sup>−1</sup> heme/non-heme diiron center. splitting Fe-O-Fe mode suggests that different conformations (<i>open</i> <i>closed</i>) are present in catalytic site enzyme. find evidence deuterium exchange experiments...
Resonance Raman and Fourier transform infrared spectroscopies have been used to study the<i>aa</i><sub>3</sub>-type cytochrome <i>c</i> oxidase the Y280H mutant from <i>Paracoccus denitrificans</i>. The stability of binuclear center in absence Tyr<sup>280</sup>-His<sup>276</sup> cross-link is not compromised since heme <i>a</i><sub>3</sub> retains same proximal environment, spin, coordination state as wild type enzyme both oxidized reduced states. We observe two C-O modes at 1966 1975...
NO laughing matter: The enzymatic production of gas (N2O) from two molecules requires the formation NN bond and subsequent cleavage NOH bond. Resonance Raman spectroscopic studies have now provided evidence for key intermediate, hyponitrite species (see optimized molecular structure), in heme a3 FeCuB binuclear center ba3-oxidoreductase Thermus thermophilus.
Time-resolved step-scan Fourier infrared spectroscopy has been used to study the CO-bound cbb3-type cytochrome c oxidase from Pseudomonas stutzeri at room temperature. We observe a single band in FTIR spectrum 1956 cm-1 (β-form). The time-resolved data indicate that upon photolysis, CO is transferred heme b3 (νCO = cm-1) CuB 2064 cm-1). decay of 2065 peak (t1/2 120 ± 16 ms) and development 144 8 ms ) suggest formation Fe−CO complex concurrent with CuB−CO complex. intensity ratio Fe−CO/CuB−CO...
Reaction pathways in the enzymatic formation and cleavage of N−N N−O bonds, respectively, are difficult to verify without structure intermediates, but we now have such information on heme a32+-NO species formed reaction ba3-oxidase with NO from resonance Raman spectroscopy. We identified His-heme a32+-NO/CuB1+ by its characteristic Fe−NO stretching frequencies at 539 1620 cm-1, respectively. The 21 7 cm-1 lower higher, than those observed Mb−NO. From these results earlier FTIR measurements,...
Identification of the intermediates and determination their structures in reduction dioxygen to water by cytochrome c oxidase (CcO) are particularly important understanding both O2 activation proton pumping enzyme. In this work, we report products rapid reaction with mixed valence form (CuA2+, heme a3+, a32+-CuB1+) The resonance Raman results show formation two ferryl-oxo species characteristic Fe(IV)=O stretching modes at 790 804 cm−1 peroxy oxidation level (PM). Density functional theory...
Understanding of the chemical nature dioxygen and nitric oxide moiety ba3 -cytochrome c oxidase from Thermus thermophilus is crucial for elucidation its physiological function. In present work, direct resonance Raman (RR) observation Fe–C–O stretching bending modes C–O mode CuB-CO complex unambiguously establishes vibrational characteristics heme-copper in ba3-oxidase. We assigned bands at 507 568 cm–1 to Fe-CO modes, respectively. The frequencies these conjunction with 1973 cm– 1 showed,...
We have identified a ligand (CO) accommodation cavity in the signal transducer sensor protein HemAT (heme-based aerotactic transducer) that allows us to gain single-molecule insights into mechanism of gas proteins. Specific mutations are distal and proximal heme were designed perturb electrostatic field near is bound accommodated cavity. report detection second site proteins which exogenous an internal The conformational gate directs ligand-migration pathway from heme, where trapped, has...
A Pseudomonas citronellolis strain was isolated from drilling waste (DW). This utilizes DW as the sole energy and carbon source to produce biosurfactants (BSs). The BS produced thermally stable, amorphous includes a peptide structure. FeSO4, FeCl3 Fe(NO3)3 were supplemented at various concentration levels assess possible enhancement of production biodegradation. limit Fe compounds between increase in formation microbial toxicity 0.1 mM. enhanced biodegradation more than doubled yield,...
Time-resolved resonance Raman (TR3) and time-resolved step-scan (TRS2) FTIR spectroscopies have been used to probe the structural dynamics at heme b3 proximal distal sites after carbon monoxide photolysis from fully reduced CO-bound nitric oxide reductase. The spectra of transient species exhibit differences relative equilibrium geometry b3. most significant these is a shift 8 cm-1 higher frequency 207 mode, 7 lower ν4 mode. Our results indicate that mode observed in equilibrium-reduced...
Fourier transform infrared (FTIR) and step-scan time-resolved FTIR difference spectra are reported for the [carbonmonoxy]cytochrome caa(3) from Thermus thermophilus. A major C-O mode of heme a(3) at 1958 cm(-1) two minor modes 1967 1975 (7:1:1) have been identified room temperature remained unchanged in H(2)O/D(2)O exchange. The observed frequencies 10 higher than those obtained previously 21 K (Einarsdóttir, O., Killough, P. M., Fee, J. A., Woodruff, W. H. (1989) Biol. Chem. 264,...
Understanding the chemical nature of nitric oxide (NO) moiety nitrosylheme copper oxidases is crucial for elucidation NO activation process. In present work, direct resonance Raman spectroscopic observation both Fe(2+)-NO and N-O stretching modes unambiguously establishes vibrational characteristics NO-bound heme in cytochrome cbb(3) from Pseudomonas stutzeri. Addition to fully reduced enzyme causes rupture proximal His-heme b(3) bond resulting formation a five-coordinate b(3)(2+)-NO species...
The determination of ligand binding properties is a key step in our understanding gas sensing and discrimination by sensory proteins. HemAT newly discovered signal transducer heme protein that recognizes O(2) discriminates against other gases such as CO NO. We have used FTIR spectroscopy on CO- NO-bound sensor domain distal mutants Y70F, T95A, R91A, L92A to gain insight into the structure iron-bound at ambient temperature. These mutations were designed perturb electrostatic field near...
The description of biological activity in heme proteins responsible for activating small molecules requires identification ligand movement into the metal and non-metal binding sites. Mechanisms nitrite reductase globins are difficult to verify without structures bound ligand, but we now have such information from resonance Raman spectroscopy on myoglobin nitrito Fe-O-N=O/2-nitrovinyl species their natural environment rather than crystals. Our results indicate that formation is pH-dependent....
We report the first vibrational study of NO bound to an oxidized heme−copper oxidase. Cytochrome cbb3 oxidase from P. stutzeri reduces both O2 and H2O N2O, respectively. The ferric nitrosyl complex exhibits ν(N−O) at 1903 cm-1. This frequency is very similar ν(NO) nitric oxide reductase, acidic form Met Mb−NO, but 18 cm-1 lower than that neutral Mb−NO. By monitoring intensity, we estimate dissociates heme b3 pocket, without binding CuB, with k = 1.8 × 10-3 s-1. Therefore, occurs site not...
Resonance Raman (RR) spectra are reported for the fully reduced carbon monoxy derivative of ba3-cytochrome c oxidase from Thermus thermophilus. The RR show formation a photolabile six-coordinate heme−CO and photostable five-coordinate heme Fe−CO species. latter species is formed by cleavage proximal Fe−His384 bond first detected in heme−copper oxidases. frequency observed at 526 cm-1 correlates with either C−O stretching modes 1967 or 1982 lie on correlation line ν(Fe−CO) vs ν(C−O) all known...
Elucidating the structure and properties of active sites in cbb3 heme-copper oxidase nitric oxide reductase (Nor) is crucial understanding reaction mechanisms oxygen reduction by both enzymes. In work here, we have applied resonance Raman (RR) spectroscopy to investigate binuclear heme b3-CuB center from Pseudomonas stutzeri dinuclear b3-FeB Nor Paracoccus denitrificans ligand-free CO-bound forms reactions with O2 NO. The RR data demonstrate that Nor/NO reaction, formation N−N bond occurs...