Results 1 - 10 of 905
Results 1 - 10 of 905. Search took: 0.023 seconds
|Sort by: date | relevance|
[en] Herein, it has been presented the results of phenological observations, and also investigated the dynamics of dose-dependent changes in the amount of free proline in beans, eggplant, cucumber, tomato, as well as in potato, the seeds, and roots, which were processed with γ rays in the sterilization dose before sowing. It has been shown that pre-sowing irradiation in high doses increases the content of proline in all studied plants. It has been established that the growth and development of plants slow down as the dose increases. It has been shown that potato tubers irradiated in a sterilization dose are not suitable for subsequent sowing.
[en] The oeX174 DNA binding protein contains two DNA binding domains, containing a series of DNA binding basic amino acids, separated by a proline-rich linker region. Within each DNA binding domain, there is a conserved glycine residue. Glycine and proline residues were mutated and the effects on virion structure were examined. Substitutions for glycine residues yield particles with similar properties to previously characterized mutants with substitutions for DNA binding residues. Both sets of mutations share a common extragenic second-site suppressor, suggesting that the defects caused by the mutant proteins are mechanistically similar. Hence, glycine residues may optimize DNA-protein contacts. The defects conferred by substitutions for proline residues appear to be fundamentally different. The properties of the mutant particles along with the atomic structure of the virion suggest that the proline residues may act to guide the packaged DNA to the adjacent fivefold related asymmetric unit, thus preventing a chaotic packaging arrangement
[en] A novel chiral ionic liquid containing proline moiety was synthesized. It can be used as a highly efficient and recyclable chiral organocatalyst for Michael addition of cyclohexanone with (E)-β-nitroalkenes in methanol at room temperature. The Michael addition affords the corresponding products in satisfactory yields of isolated products ( 78-98%) with high diastereoselectivities and excellent enantioselectivities (up to 98% dr and up to 99% ee). The catalyst can be recycled up to five times without any decrease in yields and stereoselectivities.
[en] Dipeptide-derived catalysts are of great interest in various asymmetric transformations because of their short and simple preparation and easy modification of their modular structure by using different α-amino acids. We recently reported the first example of dipeptide-catalyzed enantioselective addition of dialkylzinc to aldehydes. We have developed a novel D-Phg-L-Pro dipeptide-derived catalyst for the addition of diethylzinc to aromatic aldehydes. We also disclosed an effective chiral switching by simply modifying nonchiral part of D-Phg-L-Pro dipeptide.
[en] The E. coli protein expression system is one of the most useful methods employed for NMR sample preparation. However, the production of some recombinant proteins in E. coli is often hampered by difficulties such as low expression level and low solubility. To address these problems, a modified cold-shock expression system containing a glutathione S-transferase (GST) tag, the pCold-GST system, was investigated. The pCold-GST system successfully expressed 9 out of 10 proteins that otherwise could not be expressed using a conventional E. coli expression system. Here, we applied the pCold-GST system to 84 proteins and 78 proteins were successfully expressed in the soluble fraction. Three other cold-shock expression systems containing a maltose binding protein tag (pCold-MBP), protein G B1 domain tag (pCold-GB1) or thioredoxin tag (pCold-Trx) were also developed to improve the yield. Additionally, we show that a C-terminal proline tag, which is invisible in 1H-15N HSQC spectra, inhibits protein degradation and increases the final yield of unstable proteins. The purified proteins were amenable to NMR analyses. These data suggest that pCold expression systems combined with soluble protein tags can be utilized to improve the expression and purification of various proteins for NMR analysis.
[en] A diastereoselective practical route to functionalized spiropyrrolizidine-linked rhodanines has been developed via 1,3-dipolar cycloaddition reaction of alkylidenerhodanines with azomethine ylides, prepared in situ from L-proline and acetylenic esters, in EtOH at reflux. This protocol provided quick access to a range of structurally diverse target molecules in moderate-to-good yields. The structure of a typical product was established by X-ray crystallography. Graphic abstract: .
[en] Studies in metabolism and cancer have characterized changes in core pathways involving glucose and glutamine, emphasizing the provision of substrates for building cell mass. But recent findings suggest that pathways previously considered peripheral may play a critical role providing mechanisms for cell regulation. Several of these mechanisms involve the metabolism of non-essential amino acids, for example, the channeling of glycolytic intermediates into the serine pathway for one-carbon transfers. Historically, we proposed that the proline biosynthetic pathway participated in a metabolic interlock with glucose metabolism. The discovery that proline degradation is activated by p53 directed our attention to the initiation of apoptosis by proline oxidase/dehydrogenase. Now, however, we find that the biosynthetic mechanisms and the metabolic interlock may depend on the pathway from glutamine to proline, and it is markedly activated by the oncogene MYC. These findings add a new dimension to the proline regulatory axis in cancer and present attractive potential targets for cancer treatment.
[en] In our age, humans are increasingly often exposed to radiation which can damage important biomolecules. Such defects are generated also via slow secondary electrons. In the present thesis basic effects of electron attachment to glycine, valine and proline in gasphase are investigated. Both experimental and theoretical methods are combined to reveal the nature of the underlying processes in gas phase and microsolvation. Also results of electron attachment to musk ketone and 2,4-dinitrotoluene are presented. (author)
[de]In der heutigen Zeit ist der Mensch immer oefter Strahlungsquellen ausgesetzt, welche Schaeden bei wichtigen Biomolekuelen hervorrufen koennen. Solche Defekte werden unter anderem auch durch langsame Elektronen verursacht. In dieser Arbeit wird Elektronenanlagerung an Glycin, Valin und Prolin in der Gasphase untersucht. Experimentelle und theoretische Methoden werden kombiniert, um die zugrunde liegenden Prozesse in der Gasphase aber auch im Zustand der 'Mikrosolvation' besser zu verstehen. Ebenso werden Ergebnisse von Elektronenanlagerung an Moschus Keton und an 2,4-Dinitrotoluol praesentiert. (author)
[en] A rapid and sensitive method has been developed to assay thyrotropin releasing hormone (TRH)-degrading activity in serum. In this assay, the formation of proline, a major serum degradation product of TRH (pGlu-His-Pro-NH2), is measured. The procedure is based on the finding that proline can be readily separated from TRH with Dowex 50 by a batchwise procedure in a test tube. (Auth.)