Papers by Ryan Van Wagoner
ChemInform, 2008
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
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Tetrahedron Letters, 2011
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Structure (London, England : 1993), 2006
Attempts to access antibiotics by capturing biosynthetic genes and pathways directly from environ... more Attempts to access antibiotics by capturing biosynthetic genes and pathways directly from environmental DNA, which is overwhelmingly derived from uncultured bacteria, have revealed a large and previously unknown family of N-acyl amino acid synthases (NASs). The structure of the NAS FeeM reveals structural similarity to the GCN5-related N-acyl transferases and acylhomoserine lactone synthases. The overall structure has a central beta sheet with alpha helices on both sides. A bound product at a cleft in the beta sheet identifies the active site and the structural basis for catalysis, and sequence conservation in this region indicates a bias for recognition over speed. FeeM interacts with an acyl carrier protein (FeeL), and the structure, mutagenesis, and enzymatic measurements reveal that a small hydrophobic pocket in alpha helix 5 dominates binding of FeeM to FeeL. The structural and mechanistic analyses suggest that the products of FeeM could be bacterial signaling agents.
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Biochemistry, Jan 3, 2003
A revised, high-resolution structure of psi-conotoxin Piiie (psi-Piiie), a noncompetitive inhibit... more A revised, high-resolution structure of psi-conotoxin Piiie (psi-Piiie), a noncompetitive inhibitor of the nicotinic acetylcholine receptor (nAChR), produced through the use of NMR and molecular modeling calculations is presented. The original structures of psi-Piiie had a relatively high degree of disorder, particularly in the conformation of the disulfide bridges. Our studies utilized (13)C-labeling of selected cysteine residues allowing the resolution of all problems of resonance overlap for the cysteine residues. The improved data were used to produce a new set of structures by a molecular modeling process incorporating relaxation matrix methods for the determination of interproton distance restraints and a combination of distance geometry and simulated annealing for structure generation. The structures produced are very well converged with the RMSD of backbone atom positions of the main body of the peptide improving from 0.73 to 0.13 A. Other indicators of correlation with the ...
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Natural Product Reports, 2014
Dinoflagellates produce unique polyketides characterized by their size and complexity. The biosyn... more Dinoflagellates produce unique polyketides characterized by their size and complexity. The biosynthesis of a limited number of such metabolites has been reported, with studies largely hampered by the low yield of compounds and the severe scrambling of label in the isotopically-labeled precursors. Nonetheless, of the successful biosynthetic experiments that have been reported, many surprising and unique processes have been discovered. This knowledge has been accessed through a series of biochemical labeling studies, and while limited molecular genetic data has been amassed, it is still in the early stages of development. In an attempt to meet this challenge, this review has compared some of the biosynthetic processes with similar ones identified in other microbes such as bacteria and myxobacteria, with the idea that similar genes and enzymes are employed by dinoflagellates.
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Advances in Applied Microbiology, 2007
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Bioorganic & Medicinal Chemistry Letters, 2015
A library consisting of characterized marine natural products as well as synthetic derivatives wa... more A library consisting of characterized marine natural products as well as synthetic derivatives was screened for compounds capable of inhibiting the production of hydrogen sulfide (H2S) by cystathionine beta-synthase (CBS). Eight hits were validated and shown to inhibit CBS activity with IC50 values ranging from 83 to 187μM. The majority of hits came from a series of synthetic polyandrocarpamine derivatives. In addition, a modified fluorogenic probe for H2S detection with improved solubility in aqueous solutions is reported.
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ChemInform, 2001
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Tetrahedron Letters, 2008
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Organic Letters, 2008
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Journal of Natural Products, 2008
The biogenetic origin of the carbon atoms in the 2-azaanthraquinone scorpinone ( 1), produced by ... more The biogenetic origin of the carbon atoms in the 2-azaanthraquinone scorpinone ( 1), produced by the rare fungus Amorosia littoralis isolated from marine sediment, was explored through isotopic enrichment studies utilizing [2- (13)C]-acetate and [1,2- (13)C]-acetate. The labeling results reveal a heptaketide precursor is involved in the biosynthesis of 1, as has been found for the structurally related naphthoquinone dihydrofusarubin. The previously identified naphthoquinone herbarin ( 2) was also isolated and appears to bear the same biogenetic relationship to 1 as the fusarubins do to the fungal 2-azaanthraquinone bostrycoidins.
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Journal of Natural Products, 2010
The discovery of brevisin, the first example of an &a... more The discovery of brevisin, the first example of an "interrupted" polycyclic ether, obtained from the dinoflagellate Karenia brevis, posed some important questions regarding the mechanism of the cyclization process. Consequently, we have established absolute configurations of brevisin and its related metabolite brevisamide using a modified Mosher's esterification method. For brevisin, analysis was carried out on both the 31-monokis- and the 10,31-bis-MTPA esters. The results suggest that both metabolites, like other polyethers from K. brevis, result from polyepoxide precursors with uniform (S, S) configurations for all epoxides and provide further support for a universal stereochemical model for dinoflagellate polyether formation.
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Journal of Natural Products, 2001
The MeOH extract of an Indonesia Eudistoma sp. ascidian contained 1,3,O(7)-trimethylisoxanthopter... more The MeOH extract of an Indonesia Eudistoma sp. ascidian contained 1,3,O(7)-trimethylisoxanthopterin (1), a novel pteridine. The purification of 1 was achieved through flash C(18) chromatography and cyano HPLC. The structure was determined primarily through the use of (1)H-(13)C and (1)H-(15)N HMBC measurements and comparison with data obtained for 1,3,7-trimethylguanine (2).
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Journal of Natural Products, 2010
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Biochemistry, 2003
A novel inhibitor of nicotinic acetylcholine receptors (nAChRs), psi-conotoxin Piiif, was isolate... more A novel inhibitor of nicotinic acetylcholine receptors (nAChRs), psi-conotoxin Piiif, was isolated from the venom of Conus purpurascens and found to have the sequence GOOCCLYGSCROFOGCYNALCCRK-NH2. The sequence is highly homologous to that of psi-conotoxin Piiie, a previously identified noncompetitive inhibitor of Torpedo electroplax nAChR, also isolated from C. purpurascens. Both psi-conotoxins block Torpedo and mouse nicotinic acetylcholine receptors (nAChRs), but psi-Piiif is less potent by a factor of 10(1)-10(2). A high-resolution structure of psi-Piiif was determined by NMR and molecular modeling calculations. Psi-Piiif analogues containing [(13)C]-labeled cysteine at selected positions were synthesized to resolve spectral overlap of Cys side chain proton signals. The structures are well-converged, with backbone atom position RMSDs of 0.21 A for the main body of the peptide between residues 4 and 22 and 0.47 A for all residues. The overall backbone conformation is closely similar to psi-Piiie, the main difference being in the degree of conformational disorder at the two termini. Psi-Piiie and psi-Piiif have similar locations of positive charge density, although psi-Piiif has a lower overall charge. One disulfide bridge of psi-Piiif appears to undergo dynamic conformational fluctuations based on both the model and on experimental observation. Chimeras in which the three intercysteine loops were swapped between psi-Piiie and psi-Piiif were tested for inhibitory activity against Torpedo nAChRs. The third loop, which contains no charged residues in either peptide, is the prime determinant of potency in these psi-conotoxins.
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Journal of Natural Products, 2010
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Papers by Ryan Van Wagoner