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Glyceraldehyde-3-phosphate dehydrogenase from Thermotoga maritima: Strategies of protein stabilization 总被引:2,自引:0,他引:2
Rainer Jaenicke 《FEMS microbiology reviews》1996,18(2-3):215-224
Abstract: The molecular origin of protein stability has been the subject of active research for more than a generation (R. Jaenicke (1991) Eur. J. Biochem. 202, 715–728). Faced with the discovery of extremophiles, in recent years the problem has gained momentum, especially because of its biotechnological potential. In analyzing a number of enzymes from the hyperthermophilic bacterium Thermotoga maritima , it has become clear that the excess free energy of stabilization is equivalent to only a few weak bonds ( ΔΔG stab ≈ 50 kJ/mol). As taken from the comparison of homologous enzymes from mesophiles, thermophiles and hyperthermophiles, these accumulate from local interactions (especially ion pairs), enhanced secondary or supersecondary structure, and improved packing of domains and/or subunits, without significantly altering the overall topology. In this review, glyceraldehyde-3-phosphate dehydrogenase will be discussed as a representative example to illustrate possible adaptive strategies to the extreme thermal stress in hydrothermal vents. 相似文献
13.
Might the gravity levels found on other planets and on the moon be sufficient to provide an adequate perception of upright for astronauts? Can the amount of gravity required be predicted from the physiological threshold for linear acceleration? The perception of upright is determined not only by gravity but also visual information when available and assumptions about the orientation of the body. Here, we used a human centrifuge to simulate gravity levels from zero to earth gravity along the long-axis of the body and measured observers'' perception of upright using the Oriented Character Recognition Test (OCHART) with and without visual cues arranged to indicate a direction of gravity that differed from the body''s long axis. This procedure allowed us to assess the relative contribution of the added gravity in determining the perceptual upright. Control experiments off the centrifuge allowed us to measure the relative contributions of normal gravity, vision, and body orientation for each participant. We found that the influence of 1 g in determining the perceptual upright did not depend on whether the acceleration was created by lying on the centrifuge or by normal gravity. The 50% threshold for centrifuge-simulated gravity''s ability to influence the perceptual upright was at around 0.15 g, close to the level of moon gravity but much higher than the threshold for detecting linear acceleration along the long axis of the body. This observation may partially explain the instability of moonwalkers but is good news for future missions to Mars. 相似文献
14.
During Pavlovian incentive learning, the affective properties of rewards are thought to be transferred to their predicting cues. However, how rewards are represented emotionally in animals is widely unknown. This study sought to determine whether 50-kHz ultrasonic vocalizations (USVs) in rats may signal such a state of incentive motivation to natural, nutritional rewards. To this end, rats learned to anticipate food rewards and, across experiments, the current physiological state (deprived vs. sated), the type of learning mechanism recruited (Pavlovian vs. instrumental), the hedonic properties of UCS (low vs. high palatable food), and the availability of food reward (continued vs. discontinued) were manipulated. Overall, we found that reward-cues elicited 50-kHz calls as they were signaling a putative affective state indicative of incentive motivation in the rat. Attribution and expression of incentive salience, however, seemed not to be an unified process, and could be teased apart in two different ways: 1) under high motivational state (i.e., hunger), the attribution of incentive salience to cues occurred without being expressed at the USVs level, if reward expectations were higher than the outcome; 2) in all experiments when food rewards were devalued by satiation, reward cues were still able to elicit USVs and conditioned anticipatory activity although reward seeking and consumption were drastically weakened. Our results suggest that rats are capable of representing rewards emotionally beyond apparent, immediate physiological demands. These findings may have translational potential in uncovering mechanisms underlying aberrant and persistent motivation as observed in drug addiction, gambling, and eating disorders. 相似文献
15.
Luke Jai Wood Kerstin Dautenhahn Austen Rainer Ben Robins Hagen Lehmann Dag Sverre Syrdal 《PloS one》2013,8(3)
Robots have been used in a variety of education, therapy or entertainment contexts. This paper introduces the novel application of using humanoid robots for robot-mediated interviews. An experimental study examines how children’s responses towards the humanoid robot KASPAR in an interview context differ in comparison to their interaction with a human in a similar setting. Twenty-one children aged between 7 and 9 took part in this study. Each child participated in two interviews, one with an adult and one with a humanoid robot. Measures include the behavioural coding of the children’s behaviour during the interviews and questionnaire data. The questions in these interviews focused on a special event that had recently taken place in the school. The results reveal that the children interacted with KASPAR very similar to how they interacted with a human interviewer. The quantitative behaviour analysis reveal that the most notable difference between the interviews with KASPAR and the human were the duration of the interviews, the eye gaze directed towards the different interviewers, and the response time of the interviewers. These results are discussed in light of future work towards developing KASPAR as an ‘interviewer’ for young children in application areas where a robot may have advantages over a human interviewer, e.g. in police, social services, or healthcare applications. 相似文献
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Astrid Dürauer Dr. Sabrina Mayer Wolfgang Sprinzl Alois Jungbauer Rainer Hahn Dr. 《Biotechnology journal》2009,4(5):722-729
Efficient solubilization is a crucial step during inclusion body processing and dissolving conditions were usually empirically established. Here we describe a new methodology for rapid screening of solubilization conditions and evaluation of dissolution kinetics in microtiter plates. Increase of protein in solution over time was directly related to decrease of turbidity measured by absorbance at 600 nm. Dissolution kinetics of inclusion bodies were described by a first-order reaction kinetics, which was used for drug dissolution modeling. Reaction constants were in the range of 0.01–0.03 s–1 for buffer conditions providing sufficient solubilization power. This method is not limited to the screening of optimal buffer conditions for solubilization and can be applied for studying other parameters involved in the solubility of IBs, such as pI of the protein, influence of fermentation conditions, influence of initial protein concentration, and more. 相似文献
18.
A world-wide internet survey was conducted to test central assumptions of a recent theory of cultural transmission in minorities proposed by the authors. 844 1st to 2nd generation immigrants from a wide variety of countries recruited on a microjob platform completed a questionnaire designed to test eight hypotheses derived from the theory. Support was obtained for all hypotheses. In particular, evidence was obtained for the continued presence, in the immigrants, of the culture-transmission motive postulated by the theory: the desire to maintain the culture of origin and transmit it to the next generation. Support was also obtained for the hypothesized anchoring of the culture-transmission motive in more basic motives fulfilled by cultural groups, the relative intra- and intergenerational stability of the culture-transmission motive, and its motivating effects for action tendencies and desires that support cultural transmission under the difficult conditions of migration. Furthermore, the findings suggest that the assumption that people have a culture-transmission motive belongs to the folk psychology of sociocultural groups, and that immigrants regard the fulfillment of this desire as a moral right. 相似文献
19.
Cell-permeable peptides were evaluated for a quantitatively controlled import of small molecules. The dependence of the import efficiency on the fluorophore, on the position of the fluorophore as well as on the nature of the cargo were addressed. Cellular uptake was quantitated by flow cytometry and fluorescence correlation microscopy (FCM). Fluorophores with different spectral characteristics, covering the whole visible spectral range, were selected in order to enable the simultaneous detection of several cell-permeable peptide constructs. The transcytosis sequences were based either on the sequence of the Antennapedia homeodomain protein (AntpHD)-derived penetratin peptide or the Kaposi fibroblast growth factor (FGF)-derived membrane translocating sequence (MTS)-peptide. In general, the AntpHD-derived peptides had a three- to fourfold higher import efficiency than the MTS-derived peptides. In spite of the very different physicochemical characteristics of the fluorophores, the import efficiencies for analogues labelled at different positions within the sequence of the import peptides showed a strong positive correlation. However, even for peptide cargos of very similar size, pronounced differences in import efficiency were observed. The use of cell-permeable peptide/cargo constructs for intracellular analyses of structure-function relationships therefore requires the determination of the intracellular concentrations for each construct individually. 相似文献
20.
David M. Richardson Donald M. Iponga Núria Roura‐Pascual Rainer M. Krug Suzanne J. Milton Gregory O. Hughes Wilfried Thuiller 《Ecography》2010,33(6):1049-1061
Determining the potential range of invasive alien species under current conditions is important. However, we also need to consider future distributions under scenarios of climate change and different management interventions when formulating effective long‐term intervention strategies. This paper combines niche modelling and fine‐scale process‐based modelling to define regions at high risk of invasion and simulate likely dynamics at the landscape scale. Our study species is Schinus molle (Peruvian pepper tree; Anacardiaceae), a native of central South America, introduced to South Africa in about 1850 where it was widely planted along roads. Localities of planted and naturalized trees were mapped along 5380 km of roads – a transect that effectively samples a large part of western South Africa. Correlative modelling was used to produce profiles of present and future environmental conditions characterizing its planted and naturalized ranges. A cellular‐automata simulation model was used to estimate the dynamics of S. molle under future climates and different management scenarios. The overall potential range of S. molle in the region is predicted to shrink progressively with predicted climate change. Some of the potential range of S. molle defined based on current conditions (including areas where it is currently highly invasive) is likely to become less favourable. The species could persist where it is well established long after conditions for recruitment have deteriorated. Some areas where the species is not widely naturalized now (notably the fynbos biome) are likely to become more favourable. Our modelling approach allows for the delineation of areas likely to be invaded in future by considering a range of factors at different scales that mediate the interplay of climatic variables and other drivers that define the dimensions of human intervention such as distance from planted trees and the density of planted plants, both of which affect propagule pressure. 相似文献