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1.
Filippo Genovese Stefania Ferrari Giambattista Guaitoli Monica Caselli M. Paola Costi Glauco Ponterini 《Protein science : a publication of the Protein Society》2010,19(5):1023-1030
An ad hoc bioconjugation/fluorescence resonance energy transfer (FRET) assay has been designed to spectroscopically monitor the quaternary state of human thymidylate synthase dimeric protein. The approach enables the chemoselective engineering of allosteric residues while preserving the native protein functions through reversible masking of residues within the catalytic site, and is therefore suitable for activity/oligomerization dual assay screenings. It is applied to tag the two subunits of human thymidylate synthase at cysteines 43 and 43′ with an excitation energy donor/acceptor pair. The dimer–monomer equilibrium of the enzyme is then characterized through steady‐state fluorescence determination of the intersubunit resonance energy transfer efficiency. 相似文献
2.
Dinesh S. Bhoj 《Biometrical journal. Biometrische Zeitschrift》1989,31(3):279-288
Two statistics are proposed for testing the hypothesis of equality of the means of a bivariate normal distribution with unknown common variance and correlation coefficient when observations are missing on both variates. One of the statistics reduces to the one proposed by Bhoj (1978, 1984) when the unpaired observations on the variates are equal. The distributions of the statistics are approximated by well known distributions under the null hypothesis. The empirical powers of the tests are computed and compared with those of some known statistics. The comparison supports the use of one of the statistics proposed in this paper. 相似文献
3.
C. M. B. Duwel F. C. Visser M. J. van Eenige J. P. Roos 《Molecular and cellular biochemistry》1989,88(1-2):191-194
Summary Under normal and ischemic conditions backdiffusion of radiolabeled non-esterified fatty acids (NEFA) has been demonstrated. In the fasted normal canine heart the extraction fraction (EF) during interventions with glucose or lactate loading, vasodilation, and metabolic level augmentation was determined, and compared with the control EF. Backdiffusion alterations were deduced from the EF changes. After iv injection of 17-iodo-131 heptadecanoic acid (IHDA), 11 blood samples were drawn from aorta and coronary sinus in a time period of 60 minutes. In the control and vasodilation group the EF slowly decreased from 40 to 10%. In contrast, the EF in the noradrenaline group was constant. During glucose and lactate infusion the EF became negative within 10 min and remained negative. These results suggest that during physiological circumstances backdiffusion is determined by the metabolic level of the heart and its substrate availability. 相似文献
4.
A method has been developed for immobilisation of antisera on fresh plastic tubes through an immunochemical bridge. This type
of immobilisation has been shown to be more consistent than direct adsorption on plastic. Such immunochemically coated antisera
on plastic tube has been used in the development of a noncentrifugation radioimmunoassay. This assay system has been found
to be technically as sound as the conventional method. 相似文献
5.
E. Lendaro R. Ippoliti A. Brancaccio A. Bellelli B. Vallone G. Ivaldi G.V. Sciarratta C. Castello S. Tomova M. Brunori G. Amiconi 《生物化学与生物物理学报:疾病的分子基础》1992,1180(1):15-20
Hemoglobin Dallas, an α-chain variant with a substitution of lysine for asparagine at position 97(G4), was found to have increased oxygen affinity () and reduced Bohr effect (about 50%). Addition of allosteric effectors (such as 2,3-diphosphoglycerate, inositol hexakisphosphate and bezafibrate) led to a decrease in oxygen affinity and increase in cooperative energy. Kinetic studies at pH 7.0 and 20°C revealed that (i), the overall rate of oxygen dissociation is 1.4-fold slower than that for HbA and (ii), the carbon monoxide dissociation rate is unaffected. The abnormal properties of this hemoglobin variant can be atttributed to a more ‘relaxed’ T-state. 相似文献
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Principal component analysis of compositional data 总被引:7,自引:0,他引:7
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10.
Simon Folkard 《Chronobiology international》1989,6(1):55-64
This paper advocates the use of a pragmatic approach to the problem of masking in real-life situations involving an abrupt change in the timing of sleep, i.e. shiftwork and “jet-lag” situations. Although “pure” chronobiological research has pointed to the importance of taking masking effects into account, the techniques that it has provided for doing so are extremely difficult to apply in real-life situations. The approach advocated here is based on Wever's pioneering work, and involves estimating the normative endogenous and exogenous components of the circadian rhythm in body temperature. These estimates are then used to: (a) simulate the results of shiftwork studies; and (b) to “remove” the exogenous component in “jet-lag” studies to allow analysis of the estimated endogenous component. The simulated curves obtained cross-correlated extremely highly with published night-shift temperature curves, while the “removal” of the exogenous component resulted in very similar findings to those obtained in temporal isolation studies. It is concluded that this pragmatic approach to masking may prove extremely useful in interpreting the results of field studies of shiftwork and “jet-lag”. 相似文献