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2.
The polypeptides associated with human parainfluenza virus type 3 were identified. Five proteins were present in detergent- and salt-resistant viral cores. Of these, three proteins designated NP0, NP1, and NP2 of 68,000, 58,000, and 52,000 daltons, respectively, were stably associated with 50S RNA in CsCl gradient-purified nucleocapsids. The amounts of NP1 and NP2 were variable, and these proteins were shown to be structurally related to the major nucleocapsid protein (NP0) by partial Staphylococcus aureus V8 protease mapping. The other core proteins included a 240K protein designated L (candidate for the viral polymerase) and an 84K protein designated as the phosphoprotein (P) on the basis of a predominant incorporation of Pi. The viral envelope had four prominent proteins (72, 53, 40, and 12K) under reducing conditions of electrophoresis. The 72 and 53K proteins were specifically labeled with [3H]glucosamine and [3H]mannose. When sulfhydryl reagents were removed, a new 62K protein was visualized in place of the 72, 53, and 12K proteins. The 53 and 12K proteins were interpreted to be the two subunits (F1 and F2) of the fusion protein, and the 72K protein was designated as the HN (hemagglutinin-neuraminidase) glycoprotein. The unglycosylated 40K protein represented the viral matrix protein (M). Immunoprecipitation of infected cell lysates with rabbit hyperimmune antiserum against purified virus confirmed the viral origin of these polypeptides. 相似文献
3.
Δ2-Thiazoline-2-carboxylate, the product of the suspected physiological reaction catalyzed by
-amino acid oxidase, is stable to hydrolysis at 37°C and pH 7 or above, but it hydrolyzes readily at pH 5 or below to give a mixture of N- and S-oxalylcysteamines; the N-oxalyl derivative predominates at pH's above 1 while the S-oxyalyl compound is the major product at high acidities. The pH-rate profile looks like the superposition of two bell-shaped curves. The initial increase in the rate as the pH is lowered is controlled by a pKa of 3.95 and from pH 1 to 3 the rate is relatively constant (k = 6.7 × 10−4s−1 at 37°C and ionic strength 0.5
). Below pH 1 the rate increases again to a maximum in 1
HCl and then decreases in more highly acidic solutions. The rate of conversion of S-oxalylcysteamine to N-oxalylcysteamine is inversely proportional to the hydrogen ion concentration from pH 3 to 5 but becomes largely independent of pH from pH 1 to 2. In the pH-independent region the rate is comparable with that observed by others for S-acetylcysteamine but in the pH-dependent region the rate is 20 to 25 times faster for the oxalyl derivative than for the acetyl compound. At pH 1, N-oxalylcysteamine is partially converted to the S-oxalyl derivative but the rate of hydrolysis (k = 1.0 × 10−5s−1 at 37°C) to cysteamine and oxalate of this partially equilibrated system occurs at a comparable rate. The results of this investigation are rationalized in terms of what is known about other thiazoline hydrolyses and intramolecular S to N acyl migrations. The main differences in the present case are presumably due to the fact that thiazoline-2-carboxylate can undergo hydrolysis by two reaction manifolds, one with the carboxyl unprotonated and the other with it protonated. The relevance of these results to possible reactions of thiazoline-2-carboxylate in vivo is briefly considered. 相似文献
4.
The effect of the plasticizer di(2-ethylhexyl)phthalate on the intracellular membranes of hepatocytes was investigated. Supplementation of the diet with 2% plasticizer resulted in the appearance of a large number of peroxisomes, and the number of mitochondria was also greatly increased. No significant change in the amount or appearance of the endoplasmic reticulum was detected. The oxidation of palmitoyl-CoA in peroxisomes and the activities of carnitine-acyltransferases are increased to a great extent in both mitochondria and peroxisomes. Intact respiratory control and oxidative phosphorylation indicated that mitochondrial integrity was maintained during the induction. In microsomes, cytochrome P-450 and NADPH-cytochrome c reductase are elevated. The increased incorporation of glycerol into phospholipids indicated an increased rate of synthesis. The induction of peroxisomal and mitochondrial membranes and enzymes, but not of the membranes of the endoplasmic reticulum, by phthalate esters is an unusual and valuable induction pattern not seen with other inducers. 相似文献
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6.
Surface presentation of Shigella flexneri invasion plasmid antigens requires the products of the spa locus. 总被引:38,自引:16,他引:22 下载免费PDF全文
An avirulent, invasion plasmid insertion mutant of Shigella flexneri 5 (pHS1059) was restored to the virulence phenotype by transformation with a partial HindIII library of the wild-type invasion plasmid constructed in pBR322. Western immunoblot analysis of pHS1059 whole-cell lysates revealed that the synthesis of the invasion plasmid antigens VirG, IpaA, IpaB, IpaC, and IpaD was similar to that seen in the corresponding isogenic S. flexneri 5 virulent strain, M90T. IpaB and IpaC, however, were not present on the surface of pHS1059 as was found in M90T, suggesting that the transport or presentation of the IpaB and IpaC proteins onto the bacterial surface was defective in the mutant. pHS1059 was complemented by pWR266, which carried contiguous 1.2- and 4.1-kb HindIII fragments of the invasion plasmid. pHS1059(pWR266) cells were positive in the HeLa cell invasion assay as well as colony immunoblot and enzyme-linked immunosorbent assays, using monoclonal antibodies to IpaB and IpaC. These studies established that the antigens were expressed on the surface of the transformed bacteria. In addition, water extraction of pHS1059 and pHS1059(pWR266) whole cells, which can be used to remove IpaB and IpaC antigens from the surface of wild-type M90T bacteria, yielded significant amounts of these antigens from pHS1059(pWR266) but not from pHS1059. Minicell and DNA sequence analysis indicated that several proteins were encoded by pWR266, comprising the spa loci, which were mapped to a region approximately 18 kb upstream of the ipaBCDAR gene cluster. Subcloning and deletion analysis revealed that more than one protein was involved in complementing the Spa- phenotype in pHS1059. One of these proteins, Spa47, showed striking homology to ORF4 of the Bacillus subtilis flaA locus and the fliI gene sequence of Salmonella typhimurium, both of which bear strong resemblance to the alpha and beta subunits of bacterial, mitochondrial, and chloroplast proton-translocating F0F1 ATPases. 相似文献
7.
The molecular conformation of d1-8-isotestosterone has been determined crystallographically. Crystals of the title compound belong to the space group P21/c with a = 11.449(4), b = 10.962(4), c = 25.860(5) , β = 100.95(4)0, with two molecules in the asymmetric unit. The structure has been refined to a final R value of 0.052 for 2227 reflections. Unlike testosterone, which is a flat molecule, its 8-isomer has a folded conformation. The conformations of the ring-B in the two crystallographically independent molecules (A and B) correspond to the twist form and differ significantly from one another. 相似文献
8.
9.
Vijayakumar Maheshwari Malathi Sushil K. Jalali Dandinashivara K. Sidde Gowda Muthugounder Mohan Thiruvengadam Venkatesan 《Insect Science》2017,24(1):35-46
The brown planthopper (BPH), Nilaparvata lugens (Stål), is one of the major pests of rice throughout Asia. Extensive use of insecticides for suppressing N. lugens has resulted in the development of insecticide resistance leading to frequent control failures in the field. The aim of the present study was to evaluate resistance in the field populations of N. lugens from major rice growing states of South India to various insecticides. We also determined the activity of detoxifying enzymes (esterases [ESTs], glutathione S‐transferases [GSTs], and mixed‐function oxidases [MFOs]). Moderate levels of resistance were detected in the field populations to acephate, thiamethoxam and buprofezin (resistance factors 1.05–20.92 fold, 4.52–14.99 fold, and 1.00–18.09 fold, respectively) as compared with susceptible strain while there were low levels of resistance to imidacloprid (resistance factor 1.23–6.70 fold) and complete sensitivity to etofenoprox (resistance factor 1.05–1.66 fold). EST activities in the field populations were 1.06 to 3.09 times higher than the susceptible strain while for GST and MFO the ratios varied from 1.29 to 3.41 and 1.03 to 1.76, respectively. The EST activity was found to be correlated to acephate resistance (r = 0.999, P ≥ 0.001). The high selection pressure of organophosphate, neonicotinoid, and insect growth regulator (IGR) in the field is likely to be contributing for resistance in BPH to multiple insecticides, leading to control failures. The results obtained will be beneficial to IPM recommendations for the use of effective insecticides against BPH. 相似文献
10.
Novotnik Breda Nandy Arpita Venkatesan Senthil Velan Radović Jagoš R. Fuente Juan De la Nejadi Siavash Silva Renzo C. Kouris Angela Thangadurai Venkataraman Bryant Steven Karan Kunal Shor Roman Strous Marc Larter Stephen R. 《Reviews in Environmental Science and Biotechnology》2020,19(1):217-240
Reviews in Environmental Science and Bio/Technology - The world’s energy system is still dominated by fossil fuels. While there is a rapid reduction in the cost of renewable energy and the... 相似文献