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1.
Protein metal-binding sites. 总被引:2,自引:0,他引:2
Metal ions have a role in a variety of important functions in proteins including protein folding, assembly, stability, conformational change, and catalysis. The presence or absence of a given metal ion is crucial to the conformation or activity of over one third of all proteins. Recent developments have been made in the understanding and design of metal-binding sites in proteins, an important and rapidly advancing area of protein engineering. 相似文献
2.
Shashank Hambarde Chi-Lin Tsai Raj K. Pandita Albino Bacolla Anirban Maitra Vijay Charaka Clayton R. Hunt Rakesh Kumar Oliver Limbo Remy Le Meur Walter J. Chazin Susan E. Tsutakawa Paul Russell Katharina Schlacher Tej K. Pandita John A. Tainer 《Molecular cell》2021,81(14):2989-3006.e9
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3.
Bernd Höffken Reinhard Ködding Alexander von zur Mühlen Tainer Hehrmann Rolf-Dieter Hesch 《Biochimica et Biophysica Acta (BBA)/General Subjects》1978,539(1):114-124
The nature of the conversion of thyroxine (T4) to triiodothyronine (T3) and reverse triiodothyronine (rT3) was investigated in rat liver homogenate and microsomes. A 6-fold rise of T3 and 2.5-fold rise of rT3 levels determined by specific radioimmunoassays was observed over 6 h after the addition of T4. An enzymic process is suggested that converts T4 to T3 and rT3. For T3 the optimal pH is 6 and for rT3, 9.5. The converting activity for both T3 and rT3 is temperature dependent and can be suppressed by heat, H2O2, merthiolate and by 5-propyl-2-thiouracil. rT3 and to a lesser degree iodide, were able to inhibit the production of T3 in a dose related fashion. Therefore the pH dependendy, rT3 and iodide may regulate the availability of T3 or rT3 depending on the metabolic requirements of thyroid hormones. 相似文献
4.
Selenocysteine's mechanism of incorporation and evolution revealed in cDNAs of three glutathione peroxidases 总被引:5,自引:0,他引:5
G T Mullenbach A Tabrizi B D Irvine G I Bell J A Tainer R A Hallewell 《Protein engineering》1988,2(3):239-246
The nonsense codon, UGA, has for the first time recently been shown to encode selenocysteine in two proteins, mouse glutathione peroxidase (GSH-Px) (EC 1.11.1.9) and bacterial formate dehydrogenase. A co-translational rather than post-translational selenium-incorporation mechanism has been implicated. Furthermore, high expression levels of GSH-Px have suggested that suppression of termination is efficient and specific. We have isolated and characterized pituitary, kidney and placenta cDNAs for bovine, human and mouse GSH-Px respectively. It is demonstrated that this novel suppression event occurs in diverse tissues, in at least three mammalian species and at the translational step. Surprisingly, GSH-Px is shown to be extramitochondrially encoded, indicating a cytosolic suppression event rather than one utilizing the mitochondria's well-documented extended codon-reading ability. Sequence analysis reveals that a simple proximal contextual pattern responsible for readthrough does not exist. Analysis of predicted secondary structures of mRNAs, however, has revealed a conformation which may be unique to selenocysteine proteins and may prove useful as a tool for artificial incorporation of selenocysteines. A human intron for GSH-Px from an unspliced mRNA has been isolated whose position indicates an ancient, divergent evolutionary relationship with thioredoxin-S2, rather than an independent convergent one. 相似文献
5.
Evolution of CuZn superoxide dismutase and the Greek key beta-barrel structural motif 总被引:8,自引:0,他引:8
Detailed analysis of the CuZn superoxide dismutase (SOD) structure provides new results concerning the significance and molecular basis for sequence conservation, intron-exon boundary locations, gene duplication, and Greek key beta-barrel evolution. Using 15 aligned sequences, including a new mouse sequence, specific roles have been assigned to all 23 invariant residues and additional residues exhibiting functional equivalence. Sequence invariance is dominated by 15 residues that form the active site stereochemistry, supporting a primary biological function of superoxide dismutation. The beta-strands have no sequence insertions and deletions, whereas insertions occur within the loops connecting the beta-strands and at both termini. Thus, the beta-barrel with only four invariant residues is apparently over-determined, but dependent on multiple cooperative side chain interactions. The regions encoded by exon I, a proposed nucleation site for protein folding, and exon III, the Zn loop involved in stability and catalysis, are the major structural subdomains not included in the internal twofold axis of symmetry passing near the catalytic Cu ion. This provides strong confirmatory evidence for gene evolution by duplication and fusion followed by the addition of these two exons. The proposed evolutionary pathway explains the structural versatility of the Greek key beta-barrel through functional specialization and subdomain insertions in new loop connections, and provides a rationale for the size of the present day enzyme. 相似文献
6.
Crystallographic characterization of a Cu,Zn superoxide dismutase from Photobacterium leiognathi 总被引:1,自引:0,他引:1
S M Redford D E McRee E D Getzoff H M Steinman J A Tainer 《Journal of molecular biology》1990,212(3):449-451
Crystals of a copper-zinc superoxide dismutase from Photobacterium leiognathi, a luminescent marine bacterium that is the species-specific symbiont of the ponyfish, have been obtained from 2-methyl-2,4-pentanediol solutions. The space group was determined using screenless small-angle precession photographs, and was confirmed by analyzing area detector diffraction data with the XENGEN programs for indexing and refinement. The crystals are monoclinic, space group C2 (a = 126.4 A, b = 87.0 A, c = 44.4 A, beta = 92.8 A), and have two 32,000 Mr dimers per asymmetric unit. The crystals diffract to at least 2.7 A resolution, are resistant to radiation damage, and are suitable for determination of the structure by X-ray diffraction. 相似文献
7.
Leslie A. Kuhn Craig A. Swanson Michael E. Pique John A. Tainer Elizabeth D. Getzoff 《Proteins》1995,23(4):536-547
Water-protein interactions drive protein folding, stabilize the folded structure, and influence molecular recognition and catalysis. We analyzed the closest protein contacts of 10,837 water molecules in crystallographic structures to define a specific hydrophilicity scale reflecting specific rather than bulk solvent interactions. The tendencies of different atom and residue types to be the nearest protein neighbors of bound water molecules correlated with other hydrophobicity scales, verified the relevance of crystallographically determined water positions, and provided a direct experimental measure of water affinity in the context of the folded protein. This specific hydrophilicity was highly correlated with hydrogen-bonding capacity, and correlated better with experimental than computationally derived measures of partitioning between aqueous and organic phases. Atoms with related chemistry clustered with respect to the number of bound water molecules. Neutral and negatively charged oxygen atoms were the most hydrophilic, followed by positively-charged then neutral nitrogen atoms, followed by carbon and sulfur atoms. Agreement between observed side-chain specific hydrophilicity values and values derived from the atomic hydrophilicity scale showed that hydrophilicity values can be synthesized for different functional groups, such as unusual side or main chains, discontinuous epitopes, and drug molecules. Two methods of atomic hydrophilicity analysis provided a measure of complementarity in the interfaces of trypsin:pancreatic trypsin inhibitor and HIV protease:U-75875 inhibitor complexes. © 1995 Wiley-Liss, Inc. 相似文献
8.
M.W. Anderson D.J. Crutchley B.E. Tainer T.E. Eling 《Prostaglandins & other lipid mediators》1978,16(4):563-570
We have investigated the time course of formation of thromboxane A2, thromboxane B2, and the C-17 hydroxy fatty acid, HHT, from arachidonic acid in a washed human platelet suspension. Our results indicate that HHT is not a breakdown product of thromboxane A2, but rather thromboxane A2 decomposes exclusively into thromboxane B2. The kinetics of formation of thromboxane B2 from the endoperoxide prostaglandin H2 in human platelet microsomes was examined. Our data suggest that a bimolecular reaction is involved in the formation of thromboxane A2 from prostaglandin H2 and that thromboxane synthase is not an isomerase, but may be acting via a dismutase-type reaction. One possibility is that thromboxane and HHT are produced simultaneously from two molecules of prostaglandin H2. 相似文献
9.
The structure of human mitochondrial manganese superoxide dismutase reveals a novel tetrameric interface of two 4-helix bundles. 总被引:9,自引:0,他引:9
The 2.2 A resolution crystal structure of recombinant human manganese superoxide dismutase, a homotetrameric enzyme that protects mitochondria against oxygen-mediated free radical damage, has been determined. Within each subunit, both the N-terminal helical hairpin and C-terminal alpha/beta domains contribute ligands to the catalytic manganese site. Two identical 4-helix bundles, symmetrically assembled from the N-terminal helical hairpins, form novel tetrameric interfaces that stabilize the active sites. Structurally altered polymorphic variants with reduced activity, such as tetrameric interface mutant Ile-58 to Thr, may produce not only an early selective advantage, through enhanced cytotoxicity of tumor necrosis factor for virus-infected cells, but also detrimental effects from increased mitochondrial oxidative damage, contributing to degenerative conditions, including diabetes, aging, and Parkinson's and Alzheimer's diseases. 相似文献
10.
R P Mason B Kalyanaraman B E Tainer T E Eling 《The Journal of biological chemistry》1980,255(11):5019-5022
The ESR spin-trapping technique has been used to identify a free radical involved in the oxygenation of arachidonic acid by ram seminal vesicle microsomes. The ESR spectrum of the radical adduct indicates that a carbon-centered arachidonic acid free radical has been observed. The formation of this species is inhibited by indomethacin, but not by phenol, and it is probably the first intermediate formed during the prostaglandin synthetase-catalyzed oxidation of arachidonic acid. The chemical identity of the trapped radical was substantiated with an independent synthesis of a closely related radical adduct. 相似文献