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71.
Hannes Flckner Michael Braxenthaler Peter Lackner Markus Jaritz Maria Ortner Manfred J. Sippl 《Proteins》1995,23(3):376-386
The prediction experiment reveals that fold recognition has become a powerful tool in structural biology. We applied our fold recognition technique to 13 target sequences. In two cases, replication terminating protein and prosequence of subtilisin, the predicted structures are very similar to the experimentally determined folds. For the first time, in a public blind test, the unknown structures of proteins have been predicted ahead of experiment to an accuracy approaching molecular detail. In two other cases the approximate folds have been predicted correctly. According to the assessors there were 12 recognizable folds among the target proteins. In our postprediction analysis we find that in 7 cases our fold recognition technique is successful. In several of the remaining cases the predicted folds have interesting features in common with the experimental results. We present our procedure, discuss the results, and comment on several fundamental and technical problems encountered in fold recognition. © 1995 Wiley-Liss, Inc. 相似文献
72.
One of three nuclear localization signals of maize Activator (Ac) transposase overlaps the DNA-binding domain 总被引:5,自引:0,他引:5
Ulrich Boehm Manfred Heinlein Ute Behrens Reinhard Kunze 《The Plant journal : for cell and molecular biology》1995,7(3):441-451
The nuclear localization sequences (NLSs) of the Ac transposase (TPase) protein have been characterized by indirect immunofluorescence detection of TPase deletion derivatives and TPase/β-glucuronidase (GUS) fusion proteins in transiently transfected Petunia cells. The TPase contains three NLSs near its amino-terminal end, NLS(44–62), NLS(159–178) and NLS(174–206), each of which is sufficient to redirect GUS to the nucleus. Deletion of the N-terminal 102 TPase residues including NLS(44–62) results in strongly reduced nuclear import of the truncated TPase. NLS(44–62) and NLS(159–178) are bipartite NLSs, whereas the structure of NLS(174–206) does not allow a classification into one of the three major NLS categories. NLS(174–206) overlaps with the basic DNA-binding domain of TPase. A substitution of two amino acids in this segment (HiS191→Arg and Arg193→His) results in a total loss of DNA-binding activity, but retains reduced NLS activity. Accordingly, the two functions can be separated. In addition, we show that a NLS-deficient 71 kDa TPase derivative is co-imported into the nucleus in the presence of wildtype TPase. 相似文献
73.
Peter Singer Manfred Wirth Ute Gerike Wolfgang Gdicke Vera Moritz 《Prostaglandins & other lipid mediators》1984,27(3):375-390
The lipid content as well as the fatty acid pattern of triglycerides, free fatty acids (FFA), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were estimated in renal cortex and medulla of spontaneously hypertensive rats (SHR) and normotensive Wistar rats (WR) at 4,8,26 and 52 weeks of age. In general, the level of triglycerides in renal medulla appeared higher when compared with the cortex. On the other hand, PC and PE, increasing with age, were usually higher in the cortex. A decreased percentage of linoleic acid (LA) in triglycerides, of arachidonic acid (AA) in PC and of eicosapentaenoic acid (EPA) in triglycerides, FFA, PC and PE could be found in the kidneys of SHR at 8 weeks of age, i.e. during the development of hypertension. This was accompanied with a rise of AA in FFA of SHR at 8 weeks of age, which occurred with delay in WR (at 26 weeks of age). From the data presented it can be concluded that systematic alterations in the availability of individual polyunsaturated fatty acids (PUFA) in various renal lipids might be related to the onset of hypertension in SHR which should be elucidated in more detail. 相似文献
74.
Transient Responses of Glucose-Limited Cultures of Cytophaga johnsonae to Nutrient Excess and Starvation 总被引:2,自引:1,他引:1 下载免费PDF全文
Manfred G. Hfle 《Applied microbiology》1984,47(2):356-362
Cells from glucose-limited chemostat cultures of Cytophaga johnsonae were subjected to a sudden relaxation of substrate limitation by injecting the cells into fresh batch cultures. Starvation experiments were carried out by injecting glucose-limited cells into batch cultures lacking glucose. Transient responses of biomass, glucose uptake and mineralization, ATP content, and viability on different agar media were monitored during these nutrient-shift experiments. Cells reacted differently depending on growth rate and time spent in the chemostat. Fast-growing cells showed an immediate adaptation to the new growth conditions, despite some initial overshoot reactions in ATP and uptake potential. In contrast, slowly growing cells and long-term-adapted cells showed extensive transient growth responses. Glucose uptake and mineralization potentials changed considerably during the transient growth phase before reaching new levels. During the starvation experiments, all cell types displayed a fast decrease in ATP, but the responses of the substrate uptake and mineralization potentials were strongly dependent upon the previous growth rate. Both potentials decreased rapidly in cells with high growth rates. On the other hand, cells with low growth rates maintained 80% of their uptake and mineralization potentials after 8 h of starvation. Thus, slowly growing cells are much better adapted for starvation than are fast-growing cells. 相似文献
75.
Michael St hr Marlies Vogt-Schaden Manfred Knobloch Robert Vogel Gerry Futterman 《Biotechnic & histochemistry》1978,53(4):205-215
Eight fluorescent dye combinations for simultaneous DNA-protein staining have been evaluated spectroscopically and flow microfluoromctrically: propidium iodide (PI) with fluorescein-isothiocyanate (FITC), fluorescamine (FC), and dansylchloride (DANS); diamidinophenylindole (DAPI) with sulphorhodamin (SR101), tetramethylrhodamin isothiocyanate (TRITC), and nitroben-zodiazole (NBD); acriflavine (AF) with stilbene isothiocyanate sulphonic acid (SITS), and DAPI. Three different experimental tumor cell lines have been employed in the investigations. Simultaneous DNA-protein analyses have been carried out with the newly developed HEIFAS instrument. Spectroscopically two groups of dyes were distinguishable according to their excitation maximum below 400 nm and above 450 nm respectively. DANS and NBD were found to be unsatisfactory with respect to their protein distributions obtained by flow analysis. The remaining stains involved in the dye combinations revealed comparable flow distributions of the cellular DNA and protein content. With respect to preparation time and number of centrifugal steps involved in the staining protocols, and in connection with the stability of the dye used, the DAPI-SR101 method proved to be fastest and easiest With this combination DNA and protein flow analysis can be performed simultaneously within 30 min. 相似文献
76.
Chromosome fibers isolated from lymphocyte nuclei and prepared for electron microscopy by techniques designed to preserve their native structure have a distinctly knobby appearance, suggesting that DNA and protein are not distributed evenly along the fiber axis. Individual knobs (superbeads) are arranged in tandem and have an average diameter of about 200 Å. Mild nuclease digestion of isolated nuclei releases apparent monomer superbeads that are composed of nucleohistone particles with the properties of nucleosomes. The kinetics of digestion indicate that the superbead is a discrete structural unit containing, on the average, about eight nucleosomes. 相似文献
77.
Helmut Klocker Bernhard Auer Helmut J. Burtscher Monica Hirsch-Kauffmann Manfred Schweiger 《Molecular & general genetics : MGG》1982,188(2):309-312
Summary The UV photoproduct, thymine dimer (
), is excorporated with a remarkably low rate from the DNA of human fibroblasts grown in cell culture. An UV dose of 18 J/m2 creates 0.045%
(related to thymine). Within the first two days of repair logarithmically growing and quiescent fibroblasts exhibit the same repair rates; thereafter, the proportion of
is lower in growing cells due to recovery of DNA replication. Only about 50% of the lesions are excised within 24 h. In quiescent cells, 13% of the thymine dimers originally present can be detected as late as a week after UV-irradiation. Two distinct first-order rate constants indicate that approximately half of the dimers are less accessible to repair. Repair measured by the nucleoid decondensation technique corresponds to the faster repair rate, whereas the slow repair rate cannot be detected by this method. Saturation of repair is found beyond 27 J/m2. The remarkably slow rate of excision indicates that thymine dimers are not lethal lesions in human fibroblasts. 相似文献
78.
Manfred Schwab 《Molecular & general genetics : MGG》1982,188(3):410-417
Summary
Xiphophorus represents a valuable model for studying genomic contributions to neoplasia. For analyzing these contributions at the molecular level, basic information about the genome organization is a prerequisite. This study presents data on the organization and complexity of the genomes of three species of Xiphophorus, maculatus, variatus and helleri, representative of the problem. Their diploid nuclei, as measured in the erythrocyte, contain 1.19 pg, 1.23 pg, and 1.27 pg DNA, these values representing approximately 50% of that of birds, 20% of that of mammals. The melting curves of native, high molecular weight DNA are homogeneous, the Tm was determined for maculatus as 85.0° C (corresponding to a mean GC-content of 38.3%) for variatus as 86.0° C (GC=40.7%), for helleri as 85.0° C (GC=39.3%). Reassociation of sheared denatured DNA indicated approximately 90% single copy sequences, the remaining 10% are predominantly multiple copy sequences. The complexity of single copy DNA was determined from reassociation kinetics for maculatus as 3.97×108 base pairs, for variatus as 4.31×108 base pairs, and for helleri as 4.49×108 base pairs. The DNA of the three species upon isopycnic density gradient centrifugation in the presence of the fluorescence dye Hoechst 33258 shows in addition to the main band, two heavy (GC-rich) satellites, denoted in the order of increasing density, components I and II. Analytical centrifugation reveals for the main band DNA a buoyant density of 1.6980 gcm-3 (GC=38.7%), for component I 1.7080 gcm-3 (GC=48.9%), for component II 1.7150 gcm-3 (GC=56.1%). Each of the components comprises approximately 0.38% of the total DNA. Complete digestion of components I and II with restriction enzymes EcoRI and BamHI yields a complex banding pattern upon agarose gel-electrophoresis. A 2.4 kb fragment of component I and a 5.3 kb fragment of component II of helleri, cloned and amplified in the pBR322/E. coli RR1 system, hybridize efficiently to purified nuclei of liver. Furthermore, restriction fragments of component II DNA, transferred to nitrocellulose by Southern-blotting, hybridize with 18S and 28S ribosomal DNA. 相似文献
79.
The covalent hydration of β-halopyruvic acids and β-halopyruvamides has been investigated in the uv region by stopped-flow techniques. In aqueous solutions of β-bromopyruvate and related compounds, the geminal diol is the predominant form at all pH values. Kinetic investigations have also been carried out on these hydrations. General bases enhance the rate of approaching the equilibrium. Specific acid catalysis was not detected. In the water-catalyzed reaction of pyruvamides, the relationship between the equilibrium constants K and the rate constants of the forward reaction
shows that the transition state is more productlike. 相似文献
80.
Chromatin-bound, DNA-dependent RNA polymerase (EC 2.7.7.6) activity and chromatin template availability, as measured with saturating amounts of E. coli RNA polymerase, changes rhythmically during the formation, dormancy, and sprouting of potato tubers. Active growth processes coincide with the highest RNA polymerase activity as well as the greatest template accessibility, during tuberization and sprouting. Consequently, chromatin-associated RNA and protein content is highest in young developing tubers and in old tubers at the onset of sprouting. Ribosomal RNA content, in turn, is maximal in small tubers, remains constant during dormancy, and decreases when sprouting begins, probably due to the translocation of rRNA into the sprouts. The nucleolus changes its shape and size concomitantly with the process of tuberization. 相似文献