Michael Appell

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Many Fusarium species produce trichothecenes, sesquiterpene epoxides that differ in patterns of oxygenation and esterification at carbon positions C-3, C-4, C-7, C-8, and C-15. For the first comprehensive and quantitative comparison of the effects of oxygenation and esterification on trichothecene phytotoxicity, we tested 24 precursors, intermediates, and(More)
Tunicamycins are potent inhibitors of UDP-N-acetyl-D-hexosamine:polyprenol-phosphate N-acetylhexosamine-1-phosphate translocases (D-HexNAc-1-P translocases), a family of enzymes involved in bacterial cell wall synthesis and eukaryotic protein N-glycosylation. Structurally, tunicamycins consist of an 11-carbon dialdose core sugar called tunicamine that is(More)
The conformation and alignment of cocaine analogues bound to the monoamine transporter proteins were explored using the tensor decomposition 3-D QSAR method. It is proposed from these calculations that the bound conformation of these ligands to the three transporter proteins has the 3beta-aryl substituent in a conformation in which the aryl group is(More)
It is known that arachidonic acid, in addition to promoting release of dopamine, can inhibit its transport. The present study provides preliminary information on structure-activity relationships for uptake inhibition by rotating disk voltammetry in human embryonic kidney-293 cells expressing the human dopamine transporter. Except for anandamide, all other(More)
Cyclodextrins, cyclic oligosaccharides composed of amylose subunits, are known to interact with mycotoxins. The interactions may be useful to analytical chemists by altering the properties of the mycotoxin of interest, namely the chromatographic properties, electrophoretic properties, fluorescence, or absorption of these fungal metabolites. Practical(More)
Moniliformin is a low molecular weight mycotoxin that has worldwide potential to contaminate cereal grains. Although several traditional methods have been developed to detect moniliformin, the lack of anti-moniliformin antibodies has created a need for materials that recognize moniliformin at the molecular level through a binding mechanism. To address this(More)
A new LC method to detect fusaric acid (FA) in maize is reported based on a molecularly imprinted SPE clean-up using mimic-templated molecularly imprinted polymers. Picolinic acid was used as a toxin analog for imprinting polymers during a thermolytic synthesis. Both acidic and basic functional monomers were predicted to have favorable binding interactions(More)
Certain of the cyclodextrins are capable of significantly enhancing the native fluorescence of the estrogenic mycotoxin zearalenone (ZEN). Twenty-two cyclodextrins (CDs) were screened for their ability to enhance the fluorescence of ZEN in a capillary electrophoresis-laser induced fluorescence (CE-LIF) format. Of the CDs that were examined heptakis(More)
Geometry optimization, at the B3LYP/6-311++G** level of theory, was carried out on 4C1 and 1C4 chairs, (3,O)B and B(3,O) boats, and skew-boat conformations of alpha- and beta-D-glucopyranose. Similar calculations on 1,5-anhydro-D-glucitol allowed examination of the effect of removal of the 1-hydroxy group on the energy preference of the hydroxymethyl(More)
Alternansucrase (EC 2.4.1.140) is a d-glucansucrase that synthesizes an alternating alpha-(1-->3), (1-->6)-linked d-glucan from sucrose. It also synthesizes oligosaccharides via d-glucopyranosyl transfer to various acceptor sugars. Two of the more efficient monosaccharide acceptors are D-tagatose and L-glucose. In the presence of d-tagatose, alternansucrase(More)