27 research outputs found
Measurement of long range H,C couplings in natural products in orienting media: a tool for structure elucidation of natural products
Novel techniques for weak alignment of proteins in solution using chemical tags coordinating lanthanide ions
Mirror symmetric broadband homodecoupled perfect echo
Pulse sequences in Bruker format for achieving broadband homodecoupling in w1 is described. The technique is implemented in a conventional 2D TOCSY experiment.A real and constant time mode version of the mirror symmetric decoupling approach is provided.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV
Measurement of long range H,C couplings in natural products in orienting media: a tool for structure elucidation of natural products
In this paper we show that water insoluble compounds dissolved in poly-γ-benzyl-glutamate are amenable to the measurement of a number of homo- and heteronuclear dipolar couplings. The sensitivity and experimental precision of dipolar couplings are sufficient to obtain a good match with the structure. In order to achieve the necessary precision for H,C dipolar couplings between protons and carbons that are not directly bound a new method for the measurement of heteronuclear long range couplings is introduced that allows a one-parameter fit to a HSQC-based experiment as reference experiment. The methodology is applied to menthol (1R, 3S, 4R)
Synthesis of a novel class of carbohydrate-containing calix[4]resorcinarene adopting an asymmetrical diamond structure
Convenient synthesis of multifunctional EDTA-based chiral metal chelates substituted with an S-mesylcysteine
Svetamycins A-G, unusual piperazic acid-containing peptides from Streptomyces sp.
Seven new halogenated peptides termed svetamycins A–G (1–7) have been isolated from laboratory cultures of a Streptomyces sp. Svetamycins A–D, F, and G are cyclic depsipeptides, whereas svetamycin E is a linear analogue of svetamycin C. Their structures were determined using extensive spectroscopic analysis, and their stereochemical configuration was established by a combination of NMR data, quantum mechanical calculations, and chemical derivatizations. Svetamycins are characterized by the presence of a hydroxyl acetic acid and five amino acids including a rare 4,5-dihydroxy-2,3,4,5-tetrahydropyridazine-3-carboxylic acid, a γ-halogenated piperazic acid, and a novel δ-methylated piperazic acid in svetamycins B–C, E, and G. Moreover, isotope-labeled substrate feeding experiments demonstrated ornithine as the precursor of piperazic acid and that methylation at the δ position of the piperazyl scaffold is S-adenosyl-l-methionine (SAM)-dependent. Svetamycin G, the most potent antimicrobial of this suite of compounds, inhibited the growth of Mycobacterium smegmatis with an MIC80 value of 2 μg/mL