A new method, which employs a sequence of heteronuclear-homonuclear-heteronuclear Hartmann-Hahn (HEHOHEHAHA) cross-polarization steps for obtaining through-bond H-C-C-H correlations in larger proteins (Me > 15 kDa), is presented. The method has significantly higher sensitivity compared to INEPTHOHAHA-INEPT-based techniques. An additional feature of this experiment is that well-phaseable spectra...

The analysis of NMR spectra of med ium-size ( lo-20 kDa) proteins is often difficult because of severe signal overlap. A number of isotope-edited 2D experiments (I7) and, more recently, 3D NMR experiments have been used to alleviate this problem (8-12). Spreading spectral information in three independent frequency dimensions greatly reduces spectral overlap and thereby simplifies the process of...

One new royleanumoate, a benzene ester (1), has been isolated from T. royleanum Wall. ex Benth along with two known compounds, namely, 3,4-dihydroxymethyl benzoate (2) and oleanolic acid (3). The structure elucidation of the isolated compounds was established on two-dimensional (2D) NMR techniques including heteronuclear multiple bond correlation (HMBC), heteronuclear multiple quantum Coherence...

A new pulse sequence for high-resolution solid-state heteronuclear double-quantum MAS NMR spectroscopy of dipolar-coupled spin-12 nuclei is introduced. It is based on the five-pulse sequence known from solution-state NMR, which is here applied synchronously to both spin species. The heteronuclear double-quantum (HeDQ) spinning-sideband patterns produced by this experiment are shown to be sensit...

Six new tremulane sesquiterpenes, conocenol A-D (2-5), conocenolide A (6), and conocenolide B (7), have been isolated from cultures of the basidiomycete Conocybe siliginea. The structures of 2-7 were elucidated by the analysis of spectroscopic data, including heteronuclear multiple-bond correlation, heteronuclear single-quantum coherence, and (1)H,(1)H correlation spectroscopy, and a comparison...

We describe experiments which provide sharp chemical-shift spectra, with or without scalar couplings, for heteronuclear spin systems in inhomogeneous fields. This adds to an array of conceptual developments, beginning with the work of Maudsley and Ernst (I), which has broadened the applicability of heteronuclear NMR as a probe of complex molecules and mixtures. Sensitivity has been improved by ...

Abbreviations: CYA: czapek yeast extract agar DEPT: distortionless enhancement by polarization transfer DMF: dimethylformamide EIMS: electron-ionization mass spectrometry EtOAc: ethylacetate G25N: 25% glycerol nitrate agar HMBC: heteronuclear multiple bond correlation HMQC: heteronuclear multiple quantum coherence MEA: malt extract agar MIC: minimum inhibitory concentration NMR: nuclear magneti...

We describe a theoretical framework for understanding the heteronuclear version of the third spin assisted recoupling polarization transfer mechanism and demonstrate its potential for detecting long-distance intramolecular and intermolecular (15)N-(13)C contacts in biomolecular systems. The pulse sequence, proton assisted insensitive nuclei cross polarization (PAIN-CP) relies on a cross term be...