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Molnár Miklós Horváth Katalin Dankó Tamás Somlyai Ildikó Kovács Beáta Zs. Somlyai Gábor 《Molecular and cellular biochemistry》2021,476(12):4507-4516
Molecular and Cellular Biochemistry - Deuterium (D) is a stable isotope of hydrogen (H) with a mass number of 2. It is present in natural waters in the form of HDO, at a concentration of... 相似文献
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Hirudin inhibited the binding of human 125I-alpha-thrombin to the saturable, but not the nonsaturable, sites on washed human platelets. When hirudin was added to a thrombin-platelet mixture, it caused a biphasic dissociation of bound thrombin. A partial dissociation was too rapid to measure and was followed by complete dissociation with a first order rate constant of about 10(-2) s-1. The fraction of bound thrombin in the more slowly dissociable form increased from essentially none after a 5-s preincubation of thrombin and platelets to as much as 75% of saturable binding after a 4-min preincubation. Transition to the slowly dissociable state was not accompanied by an increase in the amount bound and was not observed with active site serine-derivatized thrombin. This is the first evidence with intact platelets of a binding characteristic that depends, as does platelet stimulation, on catalytically active thrombin, suggesting that it may represent physiologically significant receptor processing. 相似文献
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The effect of Mn2+ and Ca2+ on the kinetics of the tryptic activation of bovine trypsinogen was studied at pH 7.3 and 36.5°C. For comparison, the rate constants of autolysis and esterolytic activity of trypsin were also determined. It can be concluded that Mn2+ increases the conversion rate of trypsinogen into trypsin in a 25–40% larger extent than Ca2+. The manganese(II) ion bond to trypsinogen is supposed to keep the N-terminal part of the zymogen in a better conformation for binding at the primary and secondary binding sites of trypsin. 相似文献
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A set of scaling feedforward filters is developed in an unsupervised way via inputting pixel-discretized extended objects into a winner-take-all artificial neural network. The system discretizes the input space by both position and size. Depending on the distribution of input samples and below a certain number of neurons the spatial filters may form groups of similar filter sizes with each group covering the whole input space in a quasi-uniform fashion. Thus a multi-discretizing system may be formed. Interneural connections of scaling filters are also developed with the help of extended objects. It is shown both theoretically and with the help of numerical simulation that competitive Hebbian learning is suitable for defining neighbours for the multi-discretizing system. Taking into account the neighbouring connections between filters of similar sizes only, i.e. within the groups of filters, the system may be considered as a self-organizing multi-grid system. 相似文献
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Tamás Vajda 《Radiation and environmental biophysics》1980,18(4):275-280
Summary Influence of a homogeneous magnetic field on catalytic rate is proposed as a tool for the investigation of enzyme association. Investigations were initiated with studies of the effect of a 1.4 T homogeneous magnetic field on trypsin activity at 36.5° C and pH 3.3, 5.3, and 7.2, respectively. Periods of exposure were applied up to 2–7 h. No detectable change of activity was observed in any of the exposed systems when they were compared with the identical but unexposed ones. 相似文献
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Exonuclease V from Saccharomyces cerevisiae. A 5'----3'-deoxyribonuclease that produces dinucleotides in a sequential fashion 总被引:3,自引:0,他引:3
A novel deoxyribonuclease, exonuclease V, has been purified approximately 30,000-fold from Saccharomyces cerevisiae. Exonuclease V is localized in the nucleus. The nuclease degrades single-stranded, but not double-stranded, DNA from the 5'-end. The products of exonuclease action are dinucleotides, except the 3'-terminal tri- and tetranucleotides which are not degraded. Studies with synthetic oligo- and polynucleotides with specified sequence elements showed that exonuclease V cleaves off dinucleotides as primary digestion products. Thus, the polymers (pT)9pA(pT)n and (pT)10pA(pT)n yielded pTpA and pApT as digestion products, respectively. Removal of the 5'-terminal phosphate from the DNA substrate results in reduced binding of the enzyme to the substrate. In addition, the initial hydrolytic cut by exonuclease V on the dephosphorylated substrate produces a mixture of dinucleoside monophosphates and trinucleoside diphosphates. The enzyme is processive in action. 相似文献