PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 9887293

Solid-state dipolar INADEQUATE NMR spectroscopy with a large double-quantum spectral width.

M Hong
View original source ↗Export metadata ↓

Abstract

A technique for obtaining dipolar-mediated INADEQUATE NMR spectra with a large spectral window in the double-quantum dimension is presented. Using the dipolar recoupling sequence C7 to excite the double-quantum coherence under magic-angle spinning, the technique involves incrementing the evolution period in synchrony with the phase of the radiofrequency pulses in the C7 sequence. The technique is demonstrated on a uniformly 13C-labeled amino acid and an extensively 13C-labeled protein to identify 13C connectivity patterns for spectral assignment.

Explore related subjects

Amino AcidsCarbon IsotopesMagnetic Resonance SpectroscopyMolecular StructureProteinsComparative StudyJournal ArticleResearch Support, U.S. Gov't, Non-P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M Hong. 1999. Solid-state dipolar INADEQUATE NMR spectroscopy with a large double-quantum spectral width.. https://doi.org/10.1006/jmre.1998.1631

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2026

Chimeric structural isomer fragments as cost-efficient internal standards for amino acid quantification by mass spectrometry.

Amino acid (AA) profiles from body fluids such as blood and urine are clinical indicators for diagnosing metabolic and hepatic diseases. Current quantitative methods, such as liquid chromatography-mass spectrometry (LC-MS) with isotopically labelled internal standards (ISs), are costly and technically demanding. This study proposes a cost-efficient alternative using structural isomers as ISs in a direct liquid infusion (DLI) tandem mass spectrometry (MS/MS) approach. The method leverages chimeric spectra and fragment intensity ratios to quantify AAs, demonstrating high linearity and precision even with a 3D ion trap mass analyser. This approach offers a viable strategy for AA quantification in preventive medicine, particularly for screening metabolic diseases such as phenylketonuria, diabetes, and liver dysfunction.

Amino Acids↗
PubMed2007

MODEL-molecular descriptor lab: a web-based server for computing structural and physicochemical features of compounds.

Molecular descriptors represent structural and physicochemical features of compounds. They have been extensively used for developing statistical models, such as quantitative structure activity relationship (QSAR) and artificial neural networks (NN), for computer prediction of the pharmacodynamic, pharmacokinetic, or toxicological properties of compounds from their structure. While computer programs have been developed for computing molecular descriptors, there is a lack of a freely accessible one. We have developed a web-based server, MODEL (Molecular Descriptor Lab), for computing a comprehensive set of 3,778 molecular descriptors, which is significantly more than the approximately 1,600 molecular descriptors computed by other software. Our computational algorithms have been extensively tested and the computed molecular descriptors have been used in a number of published works of statistical models for predicting variety of pharmacodynamic, pharmacokinetic, and toxicological properties of compounds. Several testing studies on the computed molecular descriptors are discussed. MODEL is accessible at http://jing.cz3.nus.edu.sg/cgi-bin/model/model.cgi free of charge for academic use.

Amino Acids↗
PubMed2007

The penicillin G acylase production by B. megaterium is amino acid consumption dependent.

Aiming at to enhance the production of penicillin G acylase (PGA) by Bacillus megaterium, we have performed flasks experiments using different medium composition. Using 51 g/L of casein hydrolyzed with Alcalase and 2.7 g/L of phenylacetic acid (PhAc), the following carbon substrates were tested, individually and combined: glucose, glycerol, and lactose (present in cheese whey). Glycerol and glucose showed to be effective nutrients for the microorganism growth but delayed the PGA production. Cheese whey always increased enzyme production and cell mass. However, lactose (present in cheese whey) was not a significant carbon source for B. megaterium. PhAc, amino acids, and small peptides present in the hydrolyzed casein were the actual carbon sources for enzyme production. Replacement of hydrolyzed casein by free amino acids, 10.0 g/L, led to a significant increase in enzyme production (app. 150%), with a preferential consumption of alanine, aspartic acid, glycine, serine, arginine, threonine, lysine, and glutamic acid. A decrease of the enzyme production was observed when 20.0 g/L of amino acids were used. Using the single omission technique, it was shown that none of the 18 tested amino acids was essential for enzyme production. The use of a medium containing eight of the preferentially consumed amino acids lead to similar enzyme production level obtained when using 18 amino acids. PhAc, up to 2.7 g/L, did not inhibit enzyme production, even if added at the beginning of the cultivation.

Amino Acids↗