排序方式: 共有40条查询结果,搜索用时 78 毫秒
21.
One of the quinone rings of the 3,3 dimer of 2-hydroxybenzindolequinone undergoes expansion to an oxepine ring during oxidation with nitric acid. A benzisatinquinone structure was previously erroneously assigned to this compound. The structure was proved by spectral methods and stepwise degradation to be the monomeric 2-hydroxybenzindolequinone derivative. The possible oxidation pathways are discussed.See [1] for our preliminary communication.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 930–936, July, 1979. 相似文献
22.
This Letter develops an analytically tractable model for determining the equilibrium distribution of mismatch repair deficient strains in unicellular populations. The approach is based on the single fitness peak model, which has been used in Eigen's quasispecies equations in order to understand various aspects of evolutionary dynamics. As with the quasispecies model, our model for mutator-nonmutator equilibrium undergoes a phase transition in the limit of infinite sequence length. This "repair catas-trophe" occurs at a critical repair error probability of epsilon(r)=L(via)/L, where L(via) denotes the length of the genome controlling viability, while L denotes the overall length of the genome. The repair catastrophe therefore occurs when the repair error probability exceeds the fraction of deleterious mutations. Our model also gives a quantitative estimate for the equilibrium fraction of mutators in Escherichia coli. 相似文献
23.
24.
25.
L. M. Soifer M. I. Shakhnovich A. I. Chubenko A. B. Blank 《Journal of Applied Spectroscopy》1965,2(1):15-18
Optical properties are reported for LiF crystals obtained by zone melting from salts differing in synthesis and purity. The impurity distributions along the bars have been studied by chemical analysis and absorption spectrometry. The transparency is discussed as a function of the number of zone passes. 相似文献
26.
We introduce a modified version of protein lattice models in which monomers have several spin states, representing side-chain rotamers. Completion of folding corresponds to reaching the native backbone configuration with complete ordering of side chains. We find that as temperature is lowered, side-chain ordering becomes much slower than backbone folding. The presence of side chains leads to nonexponential kinetics and a broad distribution of relaxation times. 相似文献
27.
Tiana G Dokholyan NV Broglia RA Shakhnovich EI 《The Journal of chemical physics》2004,121(5):2381-2389
Explicit simulations of protein evolution, where protein chains are described at a molecular, although simplified, level provide important information to understand the similarities found to exist between known proteins. The results of such simulations suggest that a number of evolutionary-related quantities, such as the distribution of sequence similarity for structurally similar proteins, are controlled by evolutionary kinetics and do not reflect an equilibrium state. An important result for phylogeny is that a subset of the residues of each protein evolve on a much larger time scale than the other residues. 相似文献
28.
29.
O-GlcNAc transferase (OGT) is one of essential mammalian enzymes, which catalyze the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine (UDP-GlcNAc) to hydroxyl groups of serines and threonines (Ser/Thr) in proteins. Dysregulations of cellular O-GlcNAc have been implicated in diabetes, neurodegenerative disease, and cancer, which brings great interest in developing potent and speci c small-molecular OGT inhibitors. In this work, we performed virtual screening on OGT catalytic site to identify potential inhibitors. 7134792 drug-like compounds from ZINC (a free database of commercially available compounds for virtual screening) and 4287550 compounds generated by FOG (fragment optimized growth program) were screened and the top 116 compounds ranked by docking score were analyzed. By comparing the screening results, we found FOG program can generate more compounds with better docking scores than ZINC. The top ZINC compounds ranked by docking score were grouped into two classes, which held the binding positions of UDP and GlcNAc of UDPGlcNAc. Combined with individual fragments in binding pocket, de novo compounds were designed and proved to have better docking score. The screened and designed compounds may become a starting point for developing new drugs. 相似文献
30.