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51.
Solution-state structure by NMR of zinc-substituted rubredoxin from the marine hyperthermophilic archaebacterium Pyrococcus furiosus. 总被引:11,自引:8,他引:3
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P. R. Blake J. B. Park Z. H. Zhou D. R. Hare M. W. Adams M. F. Summers 《Protein science : a publication of the Protein Society》1992,1(11):1508-1521
The three-dimensional solution-state structure is reported for the zinc-substituted form of rubredoxin (Rd) from the marine hyperthermophilic archaebacterium Pyrococcus furiosus, an organism that grows optimally at 100 degrees C. Structures were generated with DSPACE by a hybrid distance geometry (DG)-based simulated annealing (SA) approach that employed 403 nuclear Overhauser effect (NOE)-derived interproton distance restraints, including 67 interresidue, 124 sequential (i-j = 1), 75 medium-range (i-j = 2-5), and 137 long-range (i-j > 5) restraints. All lower interproton distance bounds were set at the sum of the van Der Waals radii (1.8 A), and upper bounds of 2.7 A, 3.3 A, and 5.0 A were employed to represent qualitatively observed strong, medium, and weak NOE cross peak intensities, respectively. Twenty-three backbone-backbone, six backbone-sulfur (Cys), two backbone-side chain, and two side chain-side chain hydrogen bond restraints were include for structure refinement, yielding a total of 436 nonbonded restraints, which averages to > 16 restraints per residue. A total of 10 structures generated from random atom positions and 30 structures generated by molecular replacement using the backbone coordinates of Clostridium pasteurianum Rd converged to a common conformation, with the average penalty (= sum of the square of the distance bounds violations; +/- standard deviation) of 0.024 +/- 0.003 A2 and a maximum total penalty of 0.035 A2. Superposition of the backbone atoms (C, C alpha, N) of residues A1-L51 for all 40 structures afforded an average pairwise root mean square (rms) deviation value (+/- SD) of 0.42 +/- 0.07 A. Superposition of all heavy atoms for residues A1-L51, including those of structurally undefined external side chains, afforded an average pairwise rms deviation of 0.72 +/- 0.08 A. Qualitative comparison of back-calculated and experimental two-dimensional NOESY spectra indicate that the DG/SA structures are consistent with the experimental spectra. The global folding of P. furiosus Zn(Rd) is remarkably similar to the folding observed by X-ray crystallography for native Rd from the mesophilic organism C. pasteurianum, with the average rms deviation value for backbone atoms of residues A1-L51 of P. furiosus Zn(Rd) superposed with respect to residues K2-V52 of C. pasteurianum Rd of 0.77 +/- 0.06 A. The conformations of aromatic residues that compose the hydrophobic cores of the two proteins are also similar. However, P. furiosus Rd contains several unique structural elements, including at least four additional hydrogen bonds and three potential electrostatic interactions.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
52.
人体和动物模型的体表物理信息地形图的研究 总被引:1,自引:0,他引:1
对人体头面、躯干、四肢、耳廓各局部几十个及整个人体等体表部位正、背面等210个部位进行超微弱冷光和温度测量,输入电子计算机,经特殊的自编程序处理,获得十分清晰的,由3000多数据构成的各个局部或人体整体的冷光和温度地形图。 对家兔左、右耳廓、胸腹部、背部都分别观察32个部位的冷光与体表温度,经计算机分析处理,每观察区域获得约由2000个数据构成的精确的冷光、温度地形分市图。并可见不同生理、病理状态及不同病程家兔体表冷光、温度等地形图呈有规律的改变。 此外,我们还编制了以体表左右相应对称部位差值为分析数据进行地形图分析的程序,用以人体和动物体表物理信息对称规律的研究。 本工作以图形的形式显示物理参量在体表的广泛的分布规律,以揭示机体内部的不同生理、病理状态。本方法定位准确、直观醒目,为研究体表信息及机体生命活动规律提供了与逐点直接测量方法相互补充的有益的新手段。 相似文献
53.
慈竹无性系种群生长发育规律初探 总被引:18,自引:0,他引:18
慈竹(Neosinocalamus affinis)系四川分布面积最大、产量高、用途广的重要经济竹种,对振兴四川经济具有很大的潜在作用。作者引用Harper的构件结构理论,将慈竹无性系作为一个种群进行研究。以慈竹幼竹为研究对象,通过对其生长发 相似文献
54.
M. K. Chandrashekaran G. Marimuthu R. Subbaraj P. Kumarasamy M. S. Ramkumar K. Sripathi 《Journal of biosciences》1991,16(3):97-101
Several bodily functions in humans vary on a 24 h pattern and most of these variations persist with a circadian period ofca 25 h when subjects are studied under conditions of social and temporal isolation. We report in this paper that the estimates
of short time intervals (TE) of 2 h are strongly coupled to the circadian rhythm in sleepwakefulness. There is a linear correlation
between the number of hours humans stay awake (α) and their estimation of 2 h intervals. The coupling of TE to α appears to
obtain only under conditions of physical well-being. 相似文献
55.
The pathogenesis of neuronal dysfunction in the gangliosidoses is poorly understood. Studies of the feline gangliosidoses and in vitro experiments implicate ganglioside inhibition of protein kinase C (PKC) in the pathogenesis of these neurological diseases. Therefore, in the present study, the binding of [3H]phorbol-12, 13 dibutyrate was measured to determine the levels of PKC in cerebral cortex of cats with GM1 gangliosidosis (mutant) and age matched normal siblings. This binding of ([3H]PDB) to cerebral cortex homogenates in both normal and mutant cats was highly specific. The specificity of receptors was ascertained also from displacement studies using nonradioactive phorbol ester analogues to displace [3H]PDB bound to its receptors. In both mutant and normal cat brain, phorbol 12, 13-dibutyrate (PDB), 4--phorbol 12,13-didecanoate (-PDA) and 4--phorbol 12,13-dibenzoate (-PDBz) were highly potent (approximately to same degree) and effective in displacing [3H]PDB. On the other hand, 4- phorbol 12,13-diacetate (-PDA) was a weak displacer and 4--phorbol did not displace the bound [3H]PDB in either normal or mutant brain. Scatchard analysis of the binding data indicated a homogenous single class of binding sites in normal and mutant brain (Normal: Kd=1.42×10–7 M, Bmax=8.40 pmoles/mg protein. Mutant: Kd=1.60×10–7 M, Bmax=10.00 pmoles/mg protein). Sphingosine inhibited the binding to approximately the same extent in normal and mutant cortex. These studies demonstrate the presence of highly specific, homogenous, single type phorbol ester receptors in cerebral cortex of cats with GM1 gangliosidosis which are qualitatively and quantitatively similar to normal cat brain. 相似文献
56.
Sixty-nine nonmetrical morphological variants of the cranium have been studied in six samples of non-tribal, state populations
in India, and their incidence reported. Using C.A.B. Smith’s angular transformation of frequencies, the multivariate Thetasquare
distances and their respective standard deviations have been presented. On the basis of nonmetrical cranial variation, it
is clear that the samples from Uttar Pradesh, Andhra Pradesh and Bihar are closer to each other but distant from Madhya Pradesh,
Karnataka and Maharashtra. On the other hand, Karnataka and Maharashtra samples are quite close to each other and both, in
turn, are comparatively closer to Madhya Pradesh than to Uttar Pradesh, Andhra Pradesh and Bihar. Madhya Pradesh sample emerges
as the most divergent group among the six population samples studied. This, in general, is in conformity with the picture
that emerges from various analysis of morphometric and other biological data on various populations of India. 相似文献
57.
58.
Convergence of genetic distances in a migration matrix model 总被引:2,自引:0,他引:2
J W Wood 《American journal of physical anthropology》1986,71(2):209-219
A recurring problem with the use of migration matrix models of genetic differentiation has to do with their convergence properties. In practice, predictions can be drawn from these models only at equilibrium; but in the case of the standard predictors (most of which are modifications of Wright's FST), it can take an unrealistically large number of generations to approach equilibrium. An alternative set of predictors, the set of all pairwise genetic distances among the populations that define the rows and columns of the migration matrix, is investigated here. These distances are shown analytically to converge much more rapidly than the more commonly used predictors. In an application of the model to migration data on a human population from Papua New Guinea, it takes only about three to four generations for the pairwise distances to converge, in contrast to more than 100 generations for one of the standard predictors. In this case, moreover, the distances predicted by the model at equilibrium are similar to those calculated from the available genetic data. 相似文献
59.
E. Grist A. D. Woodhead C. Carlson 《In vitro cellular & developmental biology. Plant》1986,22(11):677-680
Summary Several established cell lines from different classes of vertebrates were assayed for the presence of O6-methylguanine acceptor protein. This protein is instrumental in removing adducts from DNA caused by exposure to alkylating
agents. Cultured cells had levels of acceptor protein activity within the range found in fresh tissues from animals in the
same class. We suggest that cells from lower vertebrates are satisfactory in vitro models for studies of this DNA repair function. 相似文献
60.
Jiro Hoshino 《Primates; journal of primatology》1985,26(3):248-273
A field study on the ecology of mandrills (Mandrillus sphinx) was carried out for 28 months in Cameroon. Fresh food remnants and large quantities of fresh feces were collected by following
the groups. Analyses of these products indicated that fruit (including seeds), monocotyledonous plant leaves and insects (especially
ants and termites), were frequently eaten. Mandrills mostly ate the plant and animal foods in the lower forest stratum and
on the ground. Fallen seeds and monocotyledonous plant leaves were eaten more frequently in the minor fruiting season than
in the major fruiting season presumably to compensate for the shortage of fresh fruit during the former. Daily travel distances
were shorter during the minor fruiting season than during the major fruiting season, because in the minor fruiting season
mandrills forage for small food items, such as the new leaves and piths of monocotyledons and fallen seeds which are sparsely
distributed on the ground, while in the major fruiting season they search for widely distributed food such as fruit. The daily
pattern of group movement and a food intake experiment suggest that mandrills move and feed continuously throughout the day.
Use of fallen seeds and monocotyledonous plant leaves appears to enable mandrills to maintain a terrestrial life in the tropical
rain forest. The feeding and ranging characteristics of mandrills are basically similar to those of other baboon species in
open land, though their environments differ extremely. 相似文献