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101.
102.
Stephens AN Khan MA Roucou X Nagley P Devenish RJ 《The Journal of biological chemistry》2003,278(20):17867-17875
The detailed membrane topography and neighboring polypeptides of subunit 8 in yeast mitochondrial ATP synthase have been determined using a combination of cysteine scanning mutagenesis and chemical modification. 46 single cysteine substitution mutants encompassing the length of the subunit 8 protein were constructed by site-directed mutagenesis. Expression of each cysteine variant in yeast lacking endogenous subunit 8 restored respiratory phenotype to cells and had little measurable effect on ATP hydrolase function. The exposure of each introduced cysteine residue to the aqueous environment was assessed in isolated mitochondria using the fluorescent thiol-modifying probe fluorescein 5-maleimide. The first 14 and last 13 amino acids of subunit 8 were accessible to fluorescein 5-maleimide in osmotically lysed mitochondria and are thus extrinsic to the lipid bilayer, indicating a 21-amino acid transmembrane span. The C-terminal region of subunit 8 was partially occluded by other ATP synthase subunits, especially in a small region surrounding Val-40 that was demonstrated to play an important role in maintaining the stability of the F(1)-F(0) interaction. Cross-linking using heterobifunctional reagents revealed the proximity of subunit 8 to subunits b, d, and f in the matrix and to subunits b, f, and 6 in the intermembrane space. A disulfide bridge was also formed between subunit 8(F7C) or (M10C) and residue Cys-23 of subunit 6, demonstrating a close interaction between these two hydrophobic membrane subunits and confirming the location of the N termini of each in the intermembrane space. We conclude that subunit 8 is an integral component of the stator stalk of yeast mitochondrial F(1)F(0)-ATP synthase. 相似文献
103.
Donato Santovito Virginia Egea Kiril Bidzhekov Lucia Natarelli Andr Mouro Xavier Blanchet Kanin Wichapong Maria Aslani Coy Brunßen Michael Horckmans Michael Hristov Arie Geerlof Esther Lutgens Mat J. A. P. Daemen Tilman Hackeng Christian Ries Triantafyllos Chavakis Henning Morawietz Ronald Naumann Philipp Von Hundelshausen Sabine Steffens Johan Duchêne Remco T. A. Megens Michael Sattler Christian Weber 《Autophagy》2020,16(12):2294
104.
Francisco J.L. Gordillo Carlos Jiménez Félix L. Figueroa F. Xavier Niell 《Journal of applied phycology》1998,10(5):461-469
The consequences of the addition of CO2 (1%) in cultures of S. platensis are examined in terms of biomass yield, cell composition
and external medium composition. CO2 enrichment was tested under nitrogen saturating and nitrogen limiting conditions. Increasing
CO2 levels did not cause any change in maximum growth rate while it decreased maximum biomass yield. Protein and pigments
were decreased and carbohydrate increased by high CO2, but the capability to store carbohydrates was saturated. C:N ratio
remained unchanged while organic carbon released to the external medium was enhanced, suggesting that organic carbon release
in S. platensis is an efficient mechanism for the maintenance of the metabolic integrity, balancing the cell C:N ratio in
response to environmental CO2 changes. CO2 affected the pigment content: Phycocyanin, chlorophyll and carotenoids were reduced
in around 50%, but the photosynthetic parameters were slightly changed. We propose that in S. platensis CO2 could act promoting
degradation of pigments synthetised in excess in normal CO2 conditions, that are not necessary for light harvesting. Nitrogen
assimilation was significantly not affected by CO2, and it is proposed that the inability to stimulate N assimilation by CO2
enrichment determined the lack of response in maximum growth rate.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
105.
José Rodrigues Coura Pedro Albajar Vi?as Lucia Maria Brum-Soares Andréa Silvestre de Sousa Sérgio Salles Xavier 《Memórias do Instituto Oswaldo Cruz》2013,108(8):1009-1013
A case-control study on the morbidity of Chagas heart disease was carried out in the
municipality of Barcelos in the microregion of the Rio Negro, state of Amazonas. One
hundred and six individuals, who were serologically positive for Trypanosoma
cruzi infection, as confirmed by at least two techniques with different
principles, were matched according to age and sex with an equal number of
seronegative individuals. The cases and controls were evaluated using an
epidemiological questionnaire and clinical, electrocardiograph and echocardiograph
examinations. In the seroepidemiological evaluation, 62% of the interviewees
recognised triatomines and most of them confirmed that they had seen these insects in
the piassava plantations of the riverside communities of the Negro River tributaries.
Of the seropositive patients, 25.8% affirmed that they had been stung by the
triatomines and 11.7% denied having been stung. The principal clinical manifestations
of the seropositive individuals were palpitations, chest pain and dyspnoea upon
effort. Cardiac auscultation revealed extrasystoles, bradycardia and systolic
murmurs. The electrocardiographic alterations were ventricular extrasystoles, left
and right bundle branch block, atrioventricular block and primary T wave alterations.
The echocardiogram was altered in 22.6% of the seropositive individuals and in 8.5%
of the seronegative individuals. 相似文献
106.
107.
Dynamics of transcription and mRNA export 总被引:1,自引:0,他引:1
108.
Díaz-Perales A Quesada V Peinado JR Ugalde AP Alvarez J Suárez MF Gomis-Rüth FX López-Otín C 《The Journal of biological chemistry》2005,280(34):30367-30375
Systematic analysis of degradomes, the complete protease repertoires of organisms, has demonstrated the large and growing complexity of proteolytic systems operating in all cells and tissues. We report here the identification of two new human metalloproteases that have been called archaemetzincin-1 (AMZ1) and archaemetzincin-2 (AMZ2) to emphasize their close relationship to putative proteases predicted by bioinformatic analysis of archaeal genomes. Both human proteins contain a catalytic domain with a core motif (HEXXHXXGX3CX4CXMX17CXXC) that includes an archetypal zinc-binding site, the methionine residue characteristic of metzincins, and four conserved cysteine residues that are not present at the equivalent positions of other human metalloproteases. Analysis of genome sequence databases revealed that AMZs are widely distributed in Archaea and vertebrates and contribute to the defining of a new metalloprotease family that has been called archaemetzincin. However, AMZ-like sequences are absent in a number of model organisms from bacteria to nematodes. Phylogenetic analysis showed that these enzymes have undergone a complex evolutionary process involving a series of lateral gene transfer, gene loss, and genetic duplication events that have shaped this novel family of metalloproteases. Northern blot analysis showed that AMZ1 and AMZ2 exhibit distinct expression patterns in human tissues. AMZ1 is mainly detected in liver and heart whereas AMZ2 is predominantly expressed in testis and heart, although both are also detectable at lower levels in other tissues. Both human enzymes were produced in Escherichia coli, and the purified recombinant proteins hydrolyzed synthetic substrates and bioactive peptides, demonstrating that they are functional proteases. Finally, these activities were abolished by inhibitors of metalloproteases, providing further evidence that AMZs belong to this catalytic class of proteolytic enzymes. 相似文献
109.
Hasan Jalili Seyed H. Razavi Mohammad Safari F. Xavier Malcata 《Enzyme and microbial technology》2009,45(6-7):469-476
The behavior of Bifidobacterium animalis subsp. lactis Bb 12 under batch cultivation, after continuous culturing for up to 12 d, was monitored in skim milk-based media. Previous continuous culture for longer than 6 d affected the physiology of said microorganism. The minimum inhibitory concentrations of lactic and acetic acids increased from 18 to 26 g/l, whereas the molar ratio of acetic to lactic acid increased from 0.8 to 1.55, when the previous continuous culture increased its duration from 1 to 12 d. The specific lactose consumption rate decreased from 0.94 to 0.77 glactose/gcell dry mass/h within the batch culture timeframe; this was concomitant with greater amounts of acetic and formic acids, and lower amounts of lactic acid produced. The β-galactosidase activity increased as continuous culturing time increased, and reached 446 units/ml by 12 d; however, the rate of enzyme synthesis decreased concomitantly. Succinic acid was produced during the exponential growth and stationary phases of the batch culture, but the former at exponential growth phase was higher as the continuous culturing time was longer. For comparison purposes, batch cultivation of samples taken from continuous cultures by 1 and 12 d was done using a semi-synthetic medium with glucose as carbon source; a pattern similar to that observed when using skim milk-based media was observed. 相似文献
110.
Barthélemy X Bouvier G Radunz A Docquier S Schmid GH Franck F 《Photosynthesis research》2000,64(1):63-76
The localization of protochorophyllide (Pchlide) and of NADPH-protochlorophyllide oxidoreductase (POR, EC 1.6.99.1) within
(etio)chloroplasts has been investigated at selected stages of greening of barley seedlings. Pchlide pigment and POR protein
contents were evaluated in different plastid membrane fractions by fluorescence spectroscopy and immunoblot analysis using
a monospecific polyclonal antibody raised against the purified enzyme. Fluorescence analysis showed the presence of Pchlide
in both the envelope and thylakoid membranes. During greening, the Pchlide content, expressed on a total protein basis, decreased
in thylakoid membranes, whereas it increased in the envelope membranes. POR proteins were detected mainly in thylakoid membranes
at early greening stages. In contrast, the weak amount of POR proteins was associated more specifically with envelope membranes
of mature chloroplasts. Whatever the greening stage, thylakoid-bound Pchlide and POR proteins were more abundant in the thylakoid
regions which remained unsolubilized after mild Triton treatment used as standard procedure to prepare PS II particles. This
suggests the preferential association of Pchlide and POR to the appressed regions of thylakoids.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献