Apomyoglobin
Mostrando 1-12 de 25 artigos, teses e dissertações.
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1. Mapeamento de potenciais interações envolvidas na agregação e na formação de fibrilas amilóides em apomioglobina / Mapping of potential interactions involved in apomyoglobin aggregation and amyloid fibrils formation
Proteínas enoveladas incorretamente, com freqüência levam à formação de agregados fibrilares contendo extensas estruturas em folha-β, comumente denominadas de fibrilas amilóides. A hipótese acerca da capacidade de formar fibrilas amilóides com estruturas idênticas e ricas em estruturas beta, ser uma propriedade genérica de toda proteína, apo
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 04/05/2010
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2. Fast events in protein folding: Relaxation dynamics of secondary and tertiary structure in native apomyoglobin
We report the fast relaxation dynamics of “native” apomyoglobin (pH 5.3) following a 10-ns, laser-induced temperature jump. The structural dynamics are probed using time-resolved infrared spectroscopy. The infrared kinetics monitored within the amide I absorbance of the polypeptide backbone exhibit two distinct relaxation phases which have different spec
The National Academy of Sciences of the USA.
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3. On the mechanism of the chemical and enzymic oxygenations of alpha-oxyprotohemin IX to Fe.biliverdin IX alpha.
alpha-Oxyprotohemin IX, an early intermediate in heme catabolism, was synthesized and its autoxidation to biliverdin IX alpha was studied. In anaerobic aqueous pyridine, alpha-oxyprotohemin (hexacoordinated) underwent autoreduction to yield an Fe(II) alpha-oxyprotoporphyrin pi-neutral radical bis(pyridine) complex, which reacted with an equimolar amount of d
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4. Myoglobin forms amyloid fibrils by association of unfolded polypeptide segments
Observations that β-sheet proteins form amyloid fibrils under at least partially denaturing conditions has raised questions as to whether these fibrils assemble by docking of preformed β-structure or by association of unfolded polypeptide segments. By using α-helical protein apomyoglobin, we show that the ease of fibril assembly correlates with the extent
National Academy of Sciences.
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5. Direct observation of fast protein folding: the initial collapse of apomyoglobin.
The rapid refolding dynamics of apomyoglobin are followed by a new temperature-jump fluorescence technique on a 15-ns to 0.5-ms time scale in vitro. The apparatus measures the protein-folding history in a single sweep in standard aqueous buffers. The earliest steps during folding to a compact state are observed and are complete in under 20 micros. Experiment
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6. The pKa of His-24 in the folding transition state of apomyoglobin
In native apomyoglobin, His-24 cannot be protonated, although at pH 4 the native protein forms a molten globule folding intermediate in which the histidine residues are readily protonated. The inability to protonate His-24 in the native protein dramatically affects the unfolding/refolding kinetics, as demonstrated by simulations for a simple model. Kine
The National Academy of Sciences.
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7. Folding of apominimyoglobin.
The acid unfolding pathway of apominimyoglobin (apo-mini-Mb), a 108-aa fragment (aa 32-139) of horse heart apomyoglobin has been studied by means of circular dichroism, in comparison with the native apoprotein. Similar to sperm whale apomyoglobin [Hughson, F. M., Wright, P. E. & Baldwin, R. L. (1990) Science 249, 1544-1548], a partly folded intermediate (alp
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8. Heme-protein fission under nondenaturing conditions.
Slow heme transfer from horseradish peroxidases C2 and A2, cytochrome c peroxidase, chloroperoxidase, and leghemoglobins to a heme acceptor protein, apomyoglobin, has been studied under mild conditions. The reaction is best described as heme release into water followed by quick engulfment by apomyoglobin. The energetics of the activated process are large and
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9. Evidence of nonspecific surface interactions between laser-polarized xenon and myoglobin in solution
The high sensitivity of the magnetic resonance properties of xenon to its local chemical environment and the large 129Xe NMR signals attainable through optical pumping have motivated the use of xenon as a probe of macromolecular structure and dynamics. In the present work, we report evidence for nonspecific interactions between xenon and the exterior of myog
The National Academy of Sciences.
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10. Structure and stability of a second molten globule intermediate in the apomyoglobin folding pathway.
Apomyoglobin folding proceeds through a molten globule intermediate (low-salt form; I1) that has been characterized by equilibrium (pH 4) and kinetic (pH 6) folding experiments. Of the eight alpha-helices in myoglobin, three (A, G, and H) are structured in I1, while the rest appear to be unfolded. Here we report on the structure and stability of a second int
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11. The 28–111 disulfide bond constrains the α-lactalbumin molten globule and weakens its cooperativity of folding
Our aim is to determine whether the disulfide bonds of α-lactalbumin account for the lack of cooperative folding behavior reported for some molten globule variants, in contrast to the highly cooperative folding reported for the pH 4 molten globule of apomyoglobin. Two different α-lactalbumin genetic constructs are studied: [28–111], which has a single di
The National Academy of Sciences.
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12. Probing pH and pressure effects on the apomyoglobin heme pocket with the 2'-(N,N-dimethylamino)-6-naphthoyl-4-trans-cyclohexanoic acid fluorophore.
The environmentally sensitive fluorophore 2'-(N,N-dimethylamino)-6-naphthoyl-4-trans-cyclohexanoic acid (DANCA) has been used to probe the apomyoglobin heme pocket. The unexpected polarity of this domain is generally interpreted as arising from dynamic dipolar relaxation of the peptide dipoles surrounding the heme pocket. In the present work we reexamine the