Metabonomics classifies pathways affected by bioactive compounds. Artificial neural network classification of NMR spectra of plant extracts.

The biochemical mode-of-action (MOA) for herbicides and other bioactive compounds can be rapidly and simultaneously classified by automated pattern recognition of the metabonome that is embodied in the 1H NMR spectrum of a crude plant extract. The ca. 300 herbicides that are used in agriculture today affect less than 30 different biochemical pathways.

Automated mode-of-action detection by metabolic profiling.

Rapid classification and identification of the mode-of-action of bioactive compounds applied to plants can be achieved by a robust and easy-to-use metabolic-profiling method. This method uses artificial neural network analysis of one-dimensional proton NMR spectra of aqueous plant extracts to rapidly classify changes in the total metabolic profile caused by application of crop protection chemicals.

Method performance and validation for quantitative analysis by (1)h and (31)p NMR spectroscopy. Applications to analytical standards and agricultural chemicals.

Nuclear magnetic resonance (NMR) can be used to provide an independent and intrinsically reliable determination of chemical purity. Unlike chromatography, it is possible to employ a universal reference standard as an internal standard for the majority of chemical products assayed by quantitative NMR (QNMR). This is possible because the NMR response can be made the same for all chemical components, including the internal standard, by optimizing certain instrumental parameters.

Rational molecular design and genetic engineering of herbicide resistant crops by structure modeling and site-directed mutagenesis of acetohydroxyacid synthase.

Plants with specific resistance to a single class of herbicides have been genetically engineered by introduction of genes encoding rationally designed mutant acetohydroxyacid synthase (AHAS) enzymes. Suitable substitution mutations were identified from a three-dimensional model of an AHAS-inhibitor complex. The structural model was generated based on homology to pyruvate oxidase and an imidazolinone inhibitor was positioned in the proposed binding site using structure-activity data for this class of herbicide.

A deuterium nuclear magnetic resonance study of the condensing effect of cholesterol on egg phosphatidylcholine bilayer membranes. I. Perdeuterated fatty acid probes.

Deuterium nuclear magnetic resonance quadrupole splittings Dq and the related acyl chain segmental order parameters Smol have been determined for perdeuteriostearic acid intercalated as a molecular probe in the lamellar liquid crystalline phase of egg yolk phosphatidylcholine-cholesterol-water mixtures. The 2H NMR data show that cholesterol induces a high degree of order in the acyl chains of the phospholipid while maintaining the general profile of high order near the head group and relatively low order in the middle of the bilayer. This results in a pronounced thickening of the bilayer and concomitant decrease in the average molecular area of the fatty acyl chains.

Molecular motion and order in single-bilayer vesicles and multilamellar dispersions of egg lecithin and lecithin-cholesterol mixtures. A deuterium nuclear magnetic resonance study of specifically labeled lipids.

Deuterium (2H) nuclear magnetic resonance (NMR) quadrupole splittings and relaxation times have been measured for a variety of specifically deuterated lipids intercalated in lamellar-multibilayer dispersions and single-bilayer vesicles of egg lecithin and lecithin-cholesterol mixtures. The deduced order parameters and relaxation times vary with position of deuteration, acyl chain length, unsaturation, and temperature. The order parameters and spinlattice relaxation times T1 indicate rapid intramolecular motions of restricted amplitude in both the choline head group and hydrocarbon chains.

Molecular order in Acholeplasma laidlawii membranes as determined by deuterium magnetic resonance of biosynthetically-incorporated specifically-labelled lipids.

The first application of deuterium magentic resonance of specifically labelled lipids to the study of a natural biological membrane is described. Palmitic acid labelled at the terminal methyl group with deuterium was incorporated biosynthetically into the lipids of the plasma membrane of Acholeplasma laidlawii. The deuterium nuclear magnetic resonance spectra contain quadrupole splittings which yield directly order parameters for this region of the membrane.