Reaction of substituted furan-2-carboxaldehydes and furo[b]pyrrole type aldehydes with hippuric acid.

4-Heteroarylidene-2-phenyl-1,3-oxazol-5(4H)-ones were prepared by reactions of hippuric acid with substituted furan-2-carboxaldehydes or furo[b]pyrrole type aldehydes. The reactivity of various furan-2-carboxaldehyde derivatives in this reaction is discussed. The effect of microwave irradiation on some condensation reactions was compared with "classical" conditions.

Tandem mass spectrometric analysis of a complex triterpene saponin mixture of Chenopodium quinoa.

A nano-HPLC electrospray ionization multi-stage tandem mass spectrometry (nLC-ESI-MS/MS) approach was applied to a complex crude triterpene saponin extract of Chenopodium quinoa seed coats. In ESI-MS/MS spectra of triterpene saponins, characteristic fragmentation reactions are observed and allow the determination of aglycones, saccharide sequences, compositions, and branching. Fragmentation of aglycones provided further structural information.

Molecular dynamics studies of a molecular switch in the glucocorticoid receptor.

The glucocorticoid receptor (GR) is a hormone dependent nuclear receptor that regulates gene transcription when bound to the glucocorticoid response element (GRE). The GRE acts as an allosteric effector, inducing a structural change in the GR DNA-binding domain (GR DBD) upon binding, thereby switching the GR to an active conformation. A similar conformational change can be induced by two single point mutations: Ser459Ala and Pro493Arg.

X-filtering for a range of coupling constants: application to the detection of intermolecular NOEs.

A new method for heteronuclear X-filtering is presented, which relies on repetitive applications of 90 degrees (1H)-tau(1/41J(HC))-180 degrees (1H,13C)-tau(1/41J(HC))-90 degrees (1H,13C)-PFG building blocks employing gradient-mediated suppression of magnetization built up for directly heteronuclear coupled protons. Thereby, a range of heteronuclear coupling constants can be suppressed by varying the delays of scalar coupling evolution both within and between individual transients. To achieve efficient destruction of 13C-coupled protons in macromolecular systems, the scalar coupling evolution delays were optimized using simulated annealing by including transverse relaxation effects.

Novel 12-deoxy-16-hydroxyphorbol diesters isolated from the seed oil of Jatropha curcas.

Six unstable intramolecular diterpene esters were isolated from the seed oil of Jatropha curcas. Five of these, Jatropha factors C(2)-C(6) (3-7), are new natural products, and the structure of the known Jatropha factor C(1) (2) has been revised. All compounds possess the same diterpene moiety, namely, 12-deoxy-16-hydroxyphorbol (1).

Solution structure of human apolipoprotein(a) kringle IV type 6.

The structure of apo(a) KIVT6 was investigated by two- and three-dimensional homo- and heteronuclear NMR spectroscopy. The solution structure of apo(a) KIVT6 contains only a small amount of regular secondary structure elements, comprising a short piece of antiparallel beta-sheet formed by residues Trp62-Tyr64 and Trp72-Tyr74, a short piece of parallel beta-sheet formed by the residues Cys1-Tyr2 and Thr78-Gln79, and a small 3(10)-helix within residues Thr38-Tyr40. The backbone as well as the side chains are arranged in a way similar to those of apo(a) KIVT7, apo(a) KIVT10, and plasminogen K4.