Joshua W. Bean

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RGD-containing proteins and peptides are known to bind to the platelet GPIIb/IIIa receptor and inhibit platelet aggregation. That a conformational component to the specificity exists is suggested by significantly lower activity of linear RGD analogs relative to closely related cyclic peptides and small proteins containing the RGD sequence. Recently,(More)
Carbon-13 nuclear magnetic resonance (NMR) techniques were employed to examine the effects of solvent environment on rotational barriers in two drugs known to cause widespread stimulation in the mammalian central nervous system: ethamivan and nikethamide. Total NMR bandshape analysis was performed for the exchanging alkyl carbon resonances of these(More)
Carbon-13 nuclear magnetic resonance techniques were employed to examine the effects of solvent environment on rotational barriers in a series of molecules structurally-related to the analeptic, nikethamide: N,N-dimethylnicotinamide, N,N-di-n-propylnicotinamide, and 1-nicotinoyl piperidine. Total bandshape analysis was performed for the exchanging alkyl(More)
Analysis of two isomeric cyclic hexapeptides of composition (Asp, Arg, Gly2, Pro, D-Pro) by a nuclear Overhauser effect constrained distance geometry conformation search yielded a narrowly defined backbone conformation for one and considerable ambiguity about the conformation in part of the other. Preliminary 13C relaxation studies of these peptides suggest(More)
The solution conformations in methanol and chloroform of the endothelin A receptor antagonists cyclo(dV-L-dW-dD-P), 1, and cyclo(dV-N alpha-MeL-dW-dD-P), 2, have been studied by NMR spectroscopy at room temperature and below. In these solvents, both peptides were found to have a well defined peptide backbone conformation composed of a type II beta turn at(More)
In summary, dynamic nuclear magnetic resonance techniques were used to study the hindered internal rotation of the amide bond of the analeptic nikethamide. The rotatory motion of this bond was studied in a series of solvents of increasing polarity: CDCl3, CH3(CH2)3OD, CH3CH2OD, CH3OD and D2O. Motion about the amide bond was increasingly hindered in direct(More)
Spectroscopic evidence is presented for the lack of intramolecular hydrogen bonding in a simple peptide derivative of 5,5-dimethylthiazolidine-4-carboxylic acid (Dtc). The infrared spectrum of Boc-Pro-Ile-OMe 1 in nonpolar solvents displays two N-H stretching bands at 3419 and 3330 cm-1 in CCl4 and one at 3417 and 3328 cm-1 in CHCl3. The low frequency band(More)
The eight-membered ring conformations of two diazocine turn mimics, methyl-[2,5-dioxo-3-(S)-(3-omega-tosyl-guanidino-propyl)-4-methyl-octahy dro- 1,4-diazocin-1-yl]acetate (I) and methyl-[2,5-dioxo-3-(S)-(3-omega-tosyl-guanidino-propyl)-octahydro-1,4- diazocin-1-yl]acetate (II), were determined using torsion angle constraints derived from 3J(C,H) coupling(More)
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