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Enzyme activities associated with an invertebrate iridovirus: nucleotide phosphohydrolase activity associated with iridescent virus type 6 (CIV). 总被引:1,自引:1,他引:0
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A nucleoside triphosphate phosphohydrolase activity is firmly associated with a purified invertebrate iridovirus, iridescent virus type 6. The enzyme activity hydrolyzes all the nucleoside triphosphates, but has a high preference for ATP. The products of the reaction are nucleoside diphosphates. Conditions for nucleoside triphosphate phosphohydrolase activity are described. 相似文献
5.
P Delamarche M Monnier A Gratas-Delamarche H E Koubi M H Mayet R Favier 《European journal of applied physiology and occupational physiology》1992,65(1):66-72
Ten prepubertal boys performed 60-min cycle exercise at about 60% of their maximal oxygen uptake as previously measured. To measure packed cell volume, plasma glucose, free fatty acids (FFA), glycerol and catecholamines, blood samples were drawn at rest using a heparinized catheter and at the 15th, 30th and 60th min of the exercise and after 30 min of recovery. At rest, the blood glucose concentrations were at the lowest values for normal. Exercise induced a small decrease of blood glucose which was combined with an abrupt increase of the noradrenaline concentration during the first 15 min. The FFA and glycerol concentrations increased throughout the exercise linearly with that of adrenaline. Compared to adults, the FFA uptake expressed per minute and per litre of oxygen uptake was greater in children. These results suggested that it is difficult for children to maintain a constant blood glucose concentration and that prolonged exercise provided a real stimulus to hypoglycaemia. An immediate and large increase in noradrenaline concentration during exercise and a greater utilization of FFA was probably used by children to prevent hypoglycaemia. 相似文献
6.
2-(2-Furoyl)-4(5)-(2-furanyl)-1H-imidazole (FFI) is a fluorescent molecule which was originally discovered in chloroform extract of ammoniacal solution of acid-hydrolyzed glycated proteins and proposed to represent a protein cross-link. The absence of a lysyl residue side chain and other observations promoted a detailed study of its mechanism of formation. Glycated alpha-t-Butoxycarbonyllysine was incubated for 29 days and periodically assayed for FFI and FFI-like fluorescence. Whereas fluorescence increased over time, FFI recovery was unexpectedly highest on day 0 and lowest on day 29, suggesting that FFI was directly derived from Amadori products. FFI was also recovered from hydrolysates of glycated neopentylamine, furosine, and browned poly-L-lysine but was virtually undetectable in similar solutions basified with NaOH, triethylamine, or pyridine instead of ammonia. Gas chromatography-mass spectrometry analysis of FFI from similar hydrolysates basified in the presence of 15N-enriched NH4Cl revealed for all precursors a parent ion peak at 230 instead of 228 m/e units, suggesting that the two imidazole nitrogen atoms had been incorporated from free ammonia into FFI. Spontaneous FFI synthesis occurred when furosine was reacted with aqueous ammonia at room temperature. These results do not support the proposition that FFI is an advanced glycosylation end product or a protein cross-link. They suggest that FFI is formed from ammonia and furosine which are by-products of acid-hydrolyzed glycated proteins. 相似文献
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Christopher I Keeling Macaire MS Yuen Nancy Y Liao T Roderick Docking Simon K Chan Greg A Taylor Diana L Palmquist Shaun D Jackman Anh Nguyen Maria Li Hannah Henderson Jasmine K Janes Yongjun Zhao Pawan Pandoh Richard Moore Felix AH Sperling Dezene P W Huber Inanc Birol Steven JM Jones Joerg Bohlmann 《Genome biology》2013,14(3):R27
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Ning Sui Virginie Monnier Yuriy Zakharko Yann Chevolot Sergei Alekseev Jean-Marie Bluet Vladimir Lysenko Eliane Souteyrand 《Plasmonics (Norwell, Mass.)》2013,8(1):85-92
Gold@silica core–shell nanoparticles were prepared with various gold core diameters (ranging from 20 to 150 nm) and silica thicknesses (ranging from 10 to 30 nm). When the gold diameter is increased, the size dispersion became larger, leading to a broader plasmon band. Then, silicon carbide (SiC) nanoparticles were covalently immobilized onto silica to obtain hybrid (Au@SiO2) SiC nanoparticles. The absorption properties of these hybrid nanoparticles showed that an excess of SiC nanoparticles in the dispersion can be identified by a strong absorption in the UV region. Compared to SiC reference samples, a blue shift of the fluorescence emission, from 582 to 523 nm, was observed, which was previously attributed to the strong surface modification of SiC when immobilized onto silica. Finally, the influence of several elaboration parameters (gold diameter, silica thickness, SiC concentration) on fluorescence enhancement was investigated. It showed that the highest enhancements were obtained with 10 nm silica thickness, low concentration of SiC nanoparticles, and surprisingly, with a 20-nm gold core diameter. This last result could be attributed to the broad plasmon band of big gold colloids. In this case, SiC emission strongly overlapped gold absorption, leading to possible quenching of SiC fluorescence by energy transfer. 相似文献
9.
The molecular integrity of the active site of phytases from fungi is critical for maintaining phytase function as efficient catalytic
machines. In this study, the molecular dynamics (MD) of two monomers of phytase B from Aspergillus niger, the disulfide intact
monomer (NAP) and a monomer with broken disulfide bonds (RAP), were simulated to explore the conformational basis of the
loss of catalytic activity when disulfide bonds are broken. The simulations indicated that the overall secondary and tertiary
structures of the two monomers were nearly identical but differed in some crucial secondary–structural elements in the vicinity of
the disulfide bonds and catalytic site. Disulfide bonds stabilize the β-sheet that contains residue Arg66 of the active site and
destabilize the α-helix that contains the catalytic residue Asp319. This stabilization and destabilization lead to changes in the shape
of the active–site pocket. Functionally important hydrogen bonds and atomic fluctuations in the catalytic pocket change during the
RAP simulation. None of the disulfide bonds are in or near the catalytic pocket but are most likely essential for maintaining the
native conformation of the catalytic site.
Abbreviations
PhyB - 2.5 pH acid phophatese from Aspergillus niger, NAP - disulphide intact monomer of Phytase B, RAP - disulphide reduced monomer of Phytase B, Rg - radius of gyration, RMSD - root mean square deviation, MD - molecular dynamics. 相似文献10.
KB Cullberg T Christiansen SK Paulsen JM Bruun SB Pedersen B Richelsen 《Obesity (Silver Spring, Md.)》2013,21(3):454-460