共查询到20条相似文献,搜索用时 15 毫秒
1.
The temperature dependence of the 31P NMR spectra of yeast phenylalanine tRNA, E. coli tyrosine, glutamate (2), and formylmethionine tRNA is presented. The major difference between the 31P NMR spectra of the different acceptor tRNAs is in the main cluster region between -0.5 and -1.3 ppm. This confirms an earlier assignment of the main cluster region to the undistorted phosphate diesters in the hairpin loops and helical stems. In addition the 31P NMR spectra for all tRNAs reveal approximately 16 nonhelical diester signals spread over approximately 7 ppm besides the downfield terminal 3'-phosphate monoester. In the presence of 10 mM Mg2+ most scattered and main cluster signals do not shift between 22 and 66 degrees C, thus supporting our earlier hypothesis that 31P chemical shifts are sensitive to phosphate ester torsional and bond angles. At greater than 70 degrees C, all of the signals merge into a single random-coil conformation signal. A number of the scattered peaks are shifted (0.2-1.7 ppm) and broadened between 22 and 66 degrees C in the presence of Mg2+ and spermine as a result of a conformational transition in the anticodon loop. The 31P NMR spectrum of the dimer formed between yeast tRNAPhe and E. coli tRNA 2Glu is reported. This dimer simulates codon-anticodon interaction since the anticodon triplets of the two tRNAs are complementary. Evidence is presented that the anticodon-anticodon interaction alters the anticodon conformation and partially disrupts the tertiary structure of the tRNA. 相似文献
2.
3.
Crystallization of transfer ribonucleic acids 总被引:6,自引:0,他引:6
A compilation of crystallization experiments of tRNAs published in literature as well as original results are given and discussed in this paper. Up to now 17 different tRNA species originating from Escherichia coli and from the yeast Saccharomyces cerevisiae have been crystallized. All structural tRNA families are represented, namely the tRNAs with large or small extra-loops and among them the initiator tRNAs. The tRNAs with small variable loops (4 to 5 nucleotides), e.g. tRNAAsp and tRNAPhe, yield the best diffracting crystals. Crystalline polymorphism is a common feature; about 100 different crystal forms have been observed, but only 6 among them enabled structure determination studies by X-ray diffraction. Crystallization strongly depends upon experimental parameters such as the presence of polyamines and magnesium as well as upon the purity and the molecular integrity of the tRNAs. Crystals are usually obtained by vapour diffusion methods using salts (e.g. ammonium sulfate), organic solvents (e.g. isopropanol, dioxane or 2-methyl-2,4-pentane diol) or polyethylene glycol as precipitants. A methodological strategy for crystallyzing new tRNA species is described. 相似文献
4.
5.
Mutant tyrosine transfer ribonucleic acids 总被引:11,自引:0,他引:11
J N Abelson M L Gefter L Barnett A Landy R L Russell J D Smith 《Journal of molecular biology》1970,47(1):15-28
6.
7.
Lindsay J. Sperling Andrew J. Nieuwkoop Andrew S. Lipton Deborah A. Berthold Chad M. Rienstra 《Journal of biomolecular NMR》2010,46(2):149-155
Magic-angle spinning (MAS) solid-state NMR (SSNMR) spectroscopy of uniformly-13C,15N labeled protein samples provides insight into atomic-resolution chemistry and structure. Data collection efficiency has
advanced remarkably in the last decade; however, the study of larger proteins is still challenged by relatively low resolution
in comparison to solution NMR. In this study, we present a systematic analysis of SSNMR protein spectra acquired at 11.7,
17.6 and 21.1 Tesla (1H frequencies of 500, 750, and 900 MHz). For two protein systems—GB1, a 6 kDa nanocrystalline protein and DsbA, a 21 kDa nanocrystalline
protein—line narrowing is demonstrated in all spectral regions with increasing field. Resolution enhancement is greatest in
the aliphatic region, including methine, methylene and methyl sites. The resolution for GB1 increases markedly as a function
of field, and for DsbA, resolution in the C–C region increases by 42%, according to the number of peaks that can be uniquely
picked and integrated in the 900 MHz spectra when compared to the 500 MHz spectra. Additionally, chemical exchange is uniquely
observed in the highest field spectra for at least two isoleucine Cδ1 sites in DsbA. These results further illustrate the
benefits of high-field MAS SSNMR spectroscopy for protein structural studies. 相似文献
8.
9.
More mutant tyrosine transfer ribonucleic acids 总被引:27,自引:0,他引:27
10.
Irreversible heat inactivation of transfer ribonucleic acids 总被引:8,自引:0,他引:8
T Lindahl 《The Journal of biological chemistry》1967,242(8):1970-1973
11.
12.
13.
14.
15.
High resolution solid state C NMR spectroscopy of sporopollenins from different plant taxa
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The extremely chemically resistant component of the cell wall of spores, pollens, and some microorganisms, sporopollenin, is generally accepted to be derived from carotenoids or carotenoid esters. However, we report here that 13C NMR analyses of sporopollenin from several sources shows that this widely held view is incorrect, with one possible exception. Sporopollenin is not a unique substance but rather a series of related biopolymers derived from largely saturated precursors such as fatty acids. The biopolymers contain widely varying amounts of oxygen in the form of ether, hydroxyl, carboxylic acid, ester, and ketone groups. 相似文献
16.
17.
High resolution NMR spectroscopy of physiological fluids: from metabolism to physiology. 总被引:2,自引:0,他引:2
J Vion-Dury F Nicoli G Torri J Torri M Kriat M Sciaky A Davin P Viout S Confort-Gouny P J Cozzone 《Biochimie》1992,74(9-10):801-807
High resolution NMR spectroscopy of physiological fluids provides quantitative, qualitative and dynamic information on the metabolic status of the interstitial and plasma compartments under a variety of pathophysiological conditions. The simultaneous detection and quantitation by NMR spectroscopy of numerous compounds of the intermediary metabolism offers a new insight in the understanding of the milieu intérieur. NMR spectroscopy of physiological fluids offers a unique way to define and monitor the global metabolic homeostasis in humans. The development of this analytical approach is still limited by the scarcity of pluridisciplinary teams able to fully exploit the wealth of information present on the NMR spectrum of a fluid. While application in pharmacology and toxicology is already established, the main areas of current development are cancer, hereditary metabolic disorders, organ transplantation and neurological diseases. 相似文献
18.
19.
Summary A method has been developed for the qualitative and quantitative analysis of complex isotopic mixtures of tritium-labelled amino acids and peptides by using high resolution3H NMR spectroscopy at 266.8 MHz. Determined were tritium distribution in alanine, glycine, tryptophan and 4-hydroxyproline amino acids, as well as in glycine and valine residues of peptides. Approaches have been worked out for the determination of spin coupling constants and isotope chemical shifts for the strongly coupled nonequivalent atoms of the methylene groups. 相似文献