The amino-acid sequence of the cytochrome c-553 from Desulfovibrio desulfuricans Norway has been determined and compared with that of two different cytochromes c-553 from D. vulgaris already ...described and with that cytochrome c-551 from Pseudomonas. This low-molecular-weight monohemic cytochrome comprises 80 amino acids and has the typical characteristics of small cytochromes such as mitochondrial cytochromes. Secondary-structure predictions are deduced from sequence data and are compared with X-ray three-dimensional structures of low-molecular-weight cytochrome c. The phylogenetic situation of Desulfovibrio cytochromes c-533 in the cytochrome c superfamily is discussed.
The nature of the axial ligands of a heme group is an important factor in maintaining the oxidation-reduction potential of a c-type cytochrome. Cytochrome c sub(3) from Desulfovibrio vulgaris) ...Hildenborough contains four bis-histidinyl coordinated hemes with low oxidation-reduction potentials. Site-directed mutagenesis was used to generate a mutant in which histidine 70, the sixth axial ligand of heme 4, has been replaced by a methionine. The mutant protein was expressed in Desulfovibrio desulfuricans G200 at a level similar to the wild type cytochrome. A model for the three-dimensional structure of D. vulgaris Hildenborough cytochrome c sub(3) was generated on the basis of the crystal structure of D. vulgaris) Miyazaki cytochrome c sub(3) in order to investigate the effects of the H70M mutation. The model, together with NMR data, suggested that methionine 70 has effectively replaced histidine 70 as the sixth axial ligand of heme 4 without significant alteration of the structure. A large increase of at least 200 mV of one of the four oxidation-reduction potentials was observed by electrochemistry and is interpreted in terms of structure/potential relationships.
The study of the
K
±
K
miss
0
π
∓
π
+
π
− channel (7016 events), from
pp
annihilations in a gaseous hydrogen target at NTP, with the OBELIX spectrometer at LEAR (CERN), is presented. A spin-parity ...analysis provides evidence for two axial vectors, one in the low
K
Kπ
mass region, the well established
f
1(1285), decaying to
a
0(980)
π, the second, the 1
++ component of the old puzzling
E
l
, the
f
1(1420), decaying mainly to
K
∗
K
, seen for the first time in
pp
annihilation at rest. The analysis confirms the dominant production of the pseudoscalar η(1405), decaying mainly to
(Kπ)
S
K
, and the existence of a second pseudoscalar in the same mass region, the η(1460), decaying mainly to
K
∗
K
.
A soluble c-type cytochrome was purified to homogeneity from Thiobacillus ferrooxidans. This cytochrome is characterised by an alpha -peak wavelength of 552 nm, a molecular mass of 21 193 Da (as ...determined by mass spectroscopy), and a pI value of 9. N-terminal sequencing yielded the polypeptide sequence up to the 50th residue. The iron content of 1.9 Fe/molecule and the heme/molecule ratio of 2.15 identified this cytochrome as a diheme protein. Optical redox titrations at pH 3.0 revealed the presence of two distinguishable redox species with E sub(m) = 385 mV plus or minus 20 mV and E sub(m) = 480 mV plus or minus 20 mV. EPR spectra recorded on this heme protein showed the presence of two distinct spectral species with g sub(z) = 3.1 and g sub(z) = 3.35. The g sub(z) = 3.35 heme corresponds to the higher potential redox species. In line with the differences in E sub(m) values, the two heme species were oxidised by O sub(2) with significantly differing half-times. All the above mentioned properties demonstrate that this heme protein belongs to the c sub(4) family of diheme cytochromes. The characteristics and functional role of the studied heme protein are discussed with reference to other c-type cytochromes described in Thiobacilli. Its properties are furthermore compared to other members of the cytochrome c sub(4) family.
Cytoplasmic free calcium (Ca2+i) is increased in platelets and lymphocytes of spontaneously hypertensive rats (SHR) and, to a lesser extent, in essential hypertensive patients. In this study, a ...method was devised to evaluate cellular Ca fluxes and the cellular Ca buffering power by means of the intracellular Ca indicator Quin-2. Ca influx was measured under conditions of Ca-pump inhibition, either by vanadate or ATP depletion. Lymphocytes of 5-month-old SHR were compared with those of normotensive Wistar-Kyoto rats (WKY). In both strains, the Ca entry rate and the cellular buffering capacity were higher in vanadate-treated than in ATP-depleted cells. SH rats exhibited a higher Ca influx and a greater intracellular Ca buffering power when vanadate was used to stop the Ca pump; these differences, however, were abolished in ATP-depleted lymphocytes. It is suggested that Ca entry in lymphocytes is ATP-dependent. Accelerated Ca entry in SHR can account for the previously reported higher levels of intracellular free Ca.
The amino-acid sequence of an octaheme cytochrome c3 isolated from Desulfovibrio desulfuricans Norway is presented. The protein molecule (M(r) 26,000) comprises two identical subunits of 111 amino ...acids with the characteristics typical of tetrahemic cytochrome c3 class. Comparisons between the amino-acid sequences and physiological properties of cytochrome c3 (M(r) 26,000) and cytochromes c3 (M(r) 13,000) isolated from various species of Desulfovibrio showed the existence of considerable differences. In order to distinguish between the various subclasses in the cytochrome c3 superfamily, the amino-acid sequence of cytochrome c3 (M(r) 26,000) was compared with six known cytochrome c3 (M(r) 13,000) sequences as well as with the sequence of the four c3-like domains of a high molecular weight cytochrome c (Hmc) containing 16 hemes per molecule of 65,500 Da, isolated from Desulfovibrio vulgaris Hildenborough. The evolution and phylogenetic relationships of these various polyhemic cytochromes are discussed.
The results of measuring the ratio
R =
Y(φπ
+π
−)
Y(ωπ
+π
−)
for antiproton annihilation at rest in a gaseous and a liquid hydrogen target are presented. It was found that the value of this ratio ...increases with the decrease of the dipion mass, which demonstrates the difference between the φ and ω production mechanisms. An indication of the momentum transfer dependence of the apparent OZI rule violation for the φ production from the
3
S
1 initial state was found.
This paper aims to propose the GreenMACC, an extension of MACC architecture (Metascheduling Architecture To provide QoS in Cloud Computing) aimed at providing QoS in a structure green computing ...services in a private cloud. To test the new proposed architecture, this paper presents a performance evaluation of policies of the four stages of scheduling with a focus on energy consumption and the average response time. The GreenMACC architecture was consistent in its operation allowing multiple users to run various services on a large scale private cloud and being able to control the energy consumption and quality of services.
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