Search results for "myoglobin"
showing 10 items of 141 documents
Neuroglobin and cytoglobin: fresh blood to the vertebrate globin family
2002
Neuroglobin and cytoglobin are two recently discovered members of the vertebrate globin family. Both are intracellular proteins endowed with hexacoordinated heme-Fe atoms, in their ferrous and ferric forms, and display O2 affinities comparable with that of myoglobin. Neuroglobin, which is predominantly expressed in nerve cells, is thought to protect neurons from hypoxic–ischemic injury. It is of ancient evolutionary origin, and is homologous to nerve globins of invertebrates. Cytoglobin is expressed in many different tissues, although at varying levels. It shares common ancestry with myoglobin, and can be traced to early vertebrate evolution. The physiological roles of neuroglobin and cytog…
Revisiting the thiosemicarbazonecopper(II) reaction with glutathione. Activity against colorectal carcinoma cell lines.
2018
Thiosemicarbazones (TSCs), and their copper derivatives, have been extensively studied mainly due to the potential applications as antitumor compounds. A part of the biological activity of the TSC-CuII complexes rests on their reactivity against cell reductants, as glutathione (GSH). The present paper describes the structure of the [Cu(PTSC)(ONO2)]n compound (1) (HPTSC =pyridine-2-carbaldehyde thiosemicarbazone) and its spectroscopic and magnetic properties. ESI studies performed on the reaction of GSH with 1 and the analogous [{Cu (PTSC*)(ONO2)}2] derivative (2, HPTSC* =pyridine-2-carbaldehyde 4N-methylthiosemicarbazone) show the absence of peaks related with TSC-Cu-GSH species. However GS…
Low temperature optical spectroscopy of low-spin ferric hemeproteins
1996
We report the Soret absorption spectra (500-350 nm) of the cyanomet derivatives of human hemoglobin and horse myoglobin, in the temperature range 300-20 K and in two different solvents (65% v/v glycerol-water or 65% v/v ethylene glycol-water). In order to obtain information on stereodynamic properties of active site of the two hemeproteins, we perform an analysis of the band profiles within the framework of electron-vibrations coupling. This approach enables us to single out the various contributions to the spectral bandwidth, such as those arising from non-radiative decay of the excited electronic state (homogeneous broadening) and from the coupling of the electronic transition i) with hig…
Ultrafast myoglobin structural dynamics observed with an X-ray free-electron laser.
2014
Light absorption can trigger biologically relevant protein conformational changes. The light-induced structural rearrangement at the level of a photoexcited chromophore is known to occur in the femtosecond timescale and is expected to propagate through the protein as a quake-like intramolecular motion. Here we report direct experimental evidence of such ‘proteinquake’ observed in myoglobin through femtosecond X-ray solution scattering measurements performed at the Linac Coherent Light Source X-ray free-electron laser. An ultrafast increase of myoglobin radius of gyration occurs within 1 picosecond and is followed by a delayed protein expansion. As the system approaches equilibrium it underg…
Extensive transcriptional complexity during hypoxia-regulated expression of the myoglobin gene in cancer.
2013
Recently, the ectopic expression of myoglobin (MB) was reported in human epithelial cancer cell lines and breast tumor tissues, where MB expression increased with hypoxia. The better prognosis of MB-positive breast cancer patients suggested that the globin exerts a tumor-suppressive role, possibly by impairing mitochondrial activity in hypoxic breast carcinoma cells. To better understand MB gene regulation in cancer, we systematically investigated the architecture of the human MB gene, its transcripts and promoters. In silico analysis of transcriptome data from normal human tissues and cancer cell lines, followed by RACE-PCR verification, revealed seven novel exons in the MB gene region, mo…
Mapping the network of pathways of CO diffusion in myoglobin.
2010
The pathways of diffusion of a CO molecule inside a myoglobin protein and toward the solvent are investigated. Specifically, the three-dimensional potential of mean force (PMF or free energy) of the CO molecule position inside the protein is calculated by using the single-sweep method in concert with fully resolved atomistic simulations in explicit solvent. The results are interpreted under the assumption that the diffusion of the ligand can be modeled as a navigation on the PMF in which the ligand hops between the PMF local minima following the minimum free energy paths (MFEPs) with rates set by the free energy barriers that need to be crossed. Here, all the local minima of the PMF, the MF…
Neuroglobin and Cytoglobin
2008
Neuroglobin and cytoglobin are two recent additions to the family of heme-containing respiratory proteins of man and other vertebrates. Here, we summarize the current state of knowledge of the structures, ligand-binding kinetics, evolution, and expression patterns of these two proteins. These data provide working hypotheses with regard to the possible physiological roles of these globins in the animal's metabolism. Both neuroglobin and cytoglobin are structurally similar to myoglobin, but they contain distinct features like extraordinarily high temperature resistances and unusual cavities inside the molecules. Kinetic and structural studies show that neuroglobin and cytoglobin belong to the…
Direct Evidence of the Amino Acid Side Chain and Backbone Contributions to Protein Anharmonicity
2010
Elastic incoherent neutron scattering has been used to study the temperature dependence of the mean-square displacements of nonexchangeable hydrogen atoms in powders of a series of homomeric polypeptides (polyglycine, polyalanine, polyphenylalanine and polyisoleucine) in comparison with myoglobin at the same hydration level (h = 0.2). The aim of the work was to measure the dynamic behavior of different amino acid residues separately and assess the contribution of each type of side chain to the anharmonic dynamics of proteins. The results provide direct experimental evidence that the first anharmonic activation, at approximately 150 K, is largely due to methyl group rotations entering the ti…
Coupling between the Thermal Evolution of the Heme Pocket and the External Matrix Structure in Trehalose Coated Carboxymyoglobin
2003
Proteins can assume a very large number of conformations (conformational substates), all concurring to its function. We present experimental evidence for the existence, in trehalose coated carboxymyoglobin, of a structured environment of the protein, tightly coupled to the heme pocket structure, as experienced by the bound CO molecule. This was evidenced by the strict correlation observed between the thermal evolution (300−20 K) of the CO stretching and of the water association bands in samples of carboxymyoglobin embedded in trehalose matrixes of different hydration. This observation put forward the coupling between the degrees of freedom of the matrix and those of the protein. In the drie…
Ferricytochrome c encapsulated in silica nanoparticles: structural stability and functional properties.
2004
Using a modified sol-gel technique, we have succeeded in encapsulating ferric cytochrome c in silica nanoparticles obtained from hydrolysis and polycondensation of tetramethylorthosilicate. Particles dimensions have been determined with dynamic light scattering; this technique yields an hydrodynamic radius of about 100 nm, each nanoparticle containing about 10(2)-10(3) proteins. If stored in the cold at low ionic strength, nanoparticles are stable for more than one week, even if a slow radius increase with time is observed. CD measurements show that encapsulated proteins exhibit substantially increased stability against guanidinium hydrochloride induced denaturation. Reduction kinetics of e…