PubMed · 14134184
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R ELIASSON, L THOREN, E AKERLUND. 1963-10-03. [IRRIGATING SOLUTION FOR UROLOGICAL USE].. https://pubmed.ncbi.nlm.nih.gov/14134184/
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Metabolic analysis showed a clear increase in phenylpropanoid levels in Brassica rapa leaves after treatment with methyl jasmonate. A fraction of phenylpropanoids was prepared by Diaion HP-20 and Sephadex LH-20 column chromatography after MeOH-water extraction. Even with these purification steps, isolation of each phenylpropanoid for structure elucidation is not easy due to the low levels in the plants (ca. 0.004%). A mixture was analyzed without further purification using HPLC-electrospray ionization mass spectrometry and NMR spectroscopy. Based on the NMR results including (1)H NMR, J-resolved, correlated spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), and heteronuclear multiple bond correlation (HMBC) spectra, both (1)H and (13)C resonances of the compounds were obtained. Using these NMR data, five phenylpropanoids conjugated with malate were identified: 5-hydroxyferuloyl-, caffeoyl-, coumaroyl-, feruloyl-, and sinapoyl malate. Of the compounds, 5-hydroxyferuloyl malate is a new phenylpropanoid. In addition to the five constitutive phenylpropanoids bearing trans-configuration, their cis forms, which are believed to be artifacts formed in the course of extraction steps, were also identified in the fraction.
The TaqMan quantitative PCR (QPCR) method was used to detect and quantify the 16S rRNA genes of aceticlastic methanogens at different taxonomic levels. Three different sets of primers coupled with a TaqMan probe for QPCR assays to detect the 16S rRNA genes of the order Methanosarcinales, as well as the families Methanosarcinaceae and Methanosaetaceae, were separately used. Using these primer and probe sets, the 16S rRNA genes of aceticlastic methanogens in samples from various anaerobic processes (i.e., nine pure cultures, batch experiment, and three different continuous processes including a full-scale digester), were monitored and quantified by QPCR assays. A batch experiment cultivating a mixture of aceticlastic methanogens, was conducted to monitor their population dynamics. Using this group-specific quantification method, the dynamics of a competition between two aceticlastic populations, as modulated by the acetate concentration, could well be described. The target 16S rRNA genes in environmental samples, collected from three different anaerobic processes treating sludge, cheese whey, and synthetic wastewaters, were additionally quantified. The quantified 16S rRNA gene concentrations for all samples successfully represented the community structures of the target methanogens, which were correlated accurately with the operational parameters of the anaerobic processes. It was also successful to demonstrate probe nesting of aceticlastic methanogens at the levels of order and family.
Beta-hairpins constitute the smallest beta-type structures in peptides and proteins. The development of highly stable, yet monomeric beta-hairpins based on the tryptophan zipper motif was therefore a remarkable success [A. G. Cochran, N. J. Skelton, M. A. Starovasnik, Proc. Natl. Acad. Sci USA 2001, 98, 5578-5583]. We have been able to design, synthesize and characterize a hairpin based on this motif which incorporates an azobenzene-based photoswitch, that allows for time-resolved folding studies of beta-structures with unprecedented time resolution. At room temperature the trans-azo isomer exhibits a mostly disordered structure; however, light-induced isomerization to the cis-azo form leads to a predominantly extended and parallel conformation of the two peptide parts, which are linked by the novel photoswitch, [3-(3-aminomethyl)phenylazo]phenylacetic acid (AMPP). While in the original sequence the dipeptide Asn-Gly forms a type I' beta-turn which connects the two strands of the hairpin, this role is adopted by the AMPP chromophore in our photoresponsive beta-hairpin that can apparently act as a beta I'-turn mimetic. The beta-hairpin structure was determined and confirmed by NMR spectroscopy, but the folding process can be monitored by pronounced changes in the CD, IR and fluorescence spectra. Finally, incorporation of the structurally and functionally important beta-hairpin motif into proteins by chemical ligation might allow for the photocontrol of protein structures and/or functions.