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Author

Karl V. Wood

Other affiliations: University of Minnesota
Bio: Karl V. Wood is an academic researcher from Purdue University. The author has contributed to research in topics: Mass spectrometry & Acetogenin. The author has an hindex of 36, co-authored 136 publications receiving 5186 citations. Previous affiliations of Karl V. Wood include University of Minnesota.


Papers
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TL;DR: Linear regression analysis revealed that production of methyl benzoate is regulated by the amount of benzoic acid and theamount of BAMT protein, which in turn is regulated at the transcriptional level.
Abstract: In snapdragon flowers, the volatile ester methyl benzoate is the most abundant scent compound. It is synthesized by and emitted from only the upper and lower lobes of petals, where pollinators (bumblebees) come in contact with the flower. Emission of methyl benzoate occurs in a rhythmic manner, with maximum emission during the day, which correlates with pollinator activity. A novel S-adenosyl-l-methionine:benzoic acid carboxyl methyl transferase (BAMT), the final enzyme in the biosynthesis of methyl benzoate, and its corresponding cDNA have been isolated and characterized. The complete amino acid sequence of the BAMT protein has only low levels of sequence similarity to other previously characterized proteins, including plant O-methyl transferases. During the life span of the flower, the levels of methyl benzoate emission, BAMT activity, BAMT gene expression, and the amounts of BAMT protein and benzoic acid are developmentally and differentially regulated. Linear regression analysis revealed that production of methyl benzoate is regulated by the amount of benzoic acid and the amount of BAMT protein, which in turn is regulated at the transcriptional level.

294 citations

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TL;DR: The results demonstrate the feasibility of developing transgenic plant-based production of Se-methylselenocysteine, as well as bioengineering selenite resistance in plants, and the engineering of Se tolerance in plants ideally suited for the phytoremediation of Se contaminated land.
Abstract: Background It has become increasingly evident that dietary Se plays a significant role in reducing the incidence of lung, colorectal and prostate cancer in humans. Different forms of Se vary in their chemopreventative efficacy, with Se-methylselenocysteine being one of the most potent. Interestingly, the Se accumulating plant Astragalus bisulcatus (Two-grooved poison vetch) contains up to 0.6% of its shoot dry weight as Se-methylselenocysteine. The ability of this Se accumulator to biosynthesize Se-methylselenocysteine provides a critical metabolic shunt that prevents selenocysteine and selenomethionine from entering the protein biosynthetic machinery. Such a metabolic shunt has been proposed to be vital for Se tolerance in A. bisulcatus. Utilization of this mechanism in other plants may provide a possible avenue for the genetic engineering of Se tolerance in plants ideally suited for the phytoremediation of Se contaminated land. Here, we describe the overexpression of a selenocysteine methyltransferase from A. bisulcatus to engineer Se-methylselenocysteine metabolism in the Se non-accumulator Arabidopsis thaliana (Thale cress).

266 citations

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TL;DR: Petunia hybrida cv. Mitchell phenylacetaldehyde synthase (PAAS) as discussed by the authors is a bifunctional enzyme that catalyzes the unprecedented efficient coupling of phenylalanine decarboxylation to oxidation.

233 citations

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TL;DR: The absolute configuration of the stereogenic carbinol centers in nine annonaceous acetogenins has been determined by careful 1 H- and 19 F-NMR analysis of (S)- and (R)-Mosher ester [methoxy(trifluoromethyl)phenylacetate or MTPA] derivatives as mentioned in this paper.
Abstract: The absolute configuration of the stereogenic carbinol centers in nine annonaceous acetogenins has been determined by careful 1 H- and 19 F-NMR analysis of (S)- and (R)-Mosher ester [methoxy(trifluoromethyl)phenylacetate or MTPA] derivatives. These acetogenins include five adjacent bis-tetrahydrofuran acetogenins [uvaricin (3), bullatacin (4), bullatacinone (5), asimicin (6), and rolliniastatin 1 (7)] and four mono-tetrahydrofuran acetogenins [reticulatacin (8), isoannonacin-10-one (9), annonacin-10-one (10), and annonacin (11)]

230 citations


Cited by
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TL;DR: This work develops an approach to detect noncovalent interactions in real space, based on the electron density and its derivatives, which provides a rich representation of van der Waals interactions, hydrogen bonds, and steric repulsion in small molecules, molecular complexes, and solids.
Abstract: Molecular structure does not easily identify the intricate noncovalent interactions that govern many areas of biology and chemistry, including design of new materials and drugs. We develop an approach to detect noncovalent interactions in real space, based on the electron density and its derivatives. Our approach reveals the underlying chemistry that compliments the covalent structure. It provides a rich representation of van der Waals interactions, hydrogen bonds, and steric repulsion in small molecules, molecular complexes, and solids. Most importantly, the method, requiring only knowledge of the atomic coordinates, is efficient and applicable to large systems, such as proteins or DNA. Across these applications, a view of nonbonded interactions emerges as continuous surfaces rather than close contacts between atom pairs, offering rich insight into the design of new and improved ligands.

5,731 citations

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TL;DR: In this review article, numerous examples of successful application of these compounds to improve plant stress tolerance are presented and a better understanding of the mechanisms of action of exogenously applied GB and proline is expected to aid their effective utilization in crop production in stress environments.

3,847 citations

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TL;DR: The NCI computational algorithms and their implementation for the analysis and visualization of weak interactions, using both self-consistent fully quantum-mechanical, as well as promolecular, densities are described.
Abstract: Noncovalent interactions hold the key to understanding many chemical, biological, and technological problems. Describing these noncovalent interactions accurately, including their positions in real space, constitutes a first step in the process of decoupling the complex balance of forces that define noncovalent interactions. Because of the size of macromolecules, the most common approach has been to assign van der Waals interactions (vdW), steric clashes (SC), and hydrogen bonds (HBs) based on pairwise distances between atoms according to their vdW radii. We recently developed an alternative perspective, derived from the electronic density: the non-covalent interactions (NCI) index [J. Am. Chem. Soc. 2010, 132, 6498]. This index has the dual advantages of being generally transferable to diverse chemical applications and being very fast to compute, since it can be calculated from promolecular densities. Thus, NCI analysis is applicable to large systems, including proteins and DNA, where analysis of noncova...

2,596 citations

Journal ArticleDOI
09 Jun 2005-Nature
TL;DR: Strigolactones are a group of sesquiterpene lactones, previously isolated as seed-germination stimulants for the parasitic weeds Striga and Orobanche, and a synthetic analogue, GR24, induced extensive hyphal branching in germinating spores of the AM fungus Gigaspora margarita at very low concentrations.
Abstract: Arbuscular mycorrhizal (AM) fungi form mutualistic, symbiotic associations with the roots of more than 80% of land plants. The fungi are incapable of completing their life cycle in the absence of a host root. Their spores can germinate and grow in the absence of a host, but their hyphal growth is very limited. Little is known about the molecular mechanisms that govern signalling and recognition between AM fungi and their host plants. In one of the first stages of host recognition, the hyphae of AM fungi show extensive branching in the vicinity of host roots before formation of the appressorium, the structure used to penetrate the plant root. Host roots are known to release signalling molecules that trigger hyphal branching, but these branching factors have not been isolated. Here we have isolated a branching factor from the root exudates of Lotus japonicus and used spectroscopic analysis and chemical synthesis to identify it as a strigolactone, 5-deoxy-strigol. Strigolactones are a group of sesquiterpene lactones, previously isolated as seed-germination stimulants for the parasitic weeds Striga and Orobanche. The natural strigolactones 5-deoxy-strigol, sorgolactone and strigol, and a synthetic analogue, GR24, induced extensive hyphal branching in germinating spores of the AM fungus Gigaspora margarita at very low concentrations.

1,982 citations

Journal ArticleDOI
TL;DR: It is concluded that although there are a number of promising selection criteria, the complex physiology of salt tolerance and the variation between species make it difficult to identify single criteria.

1,946 citations