Geza Toth
University of Arizona
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Featured researches published by Geza Toth.
Tetrahedron Letters | 1989
Ramalinga Dharanipragada; Ernesto Nicolas; Geza Toth; Victor J. Hruby
Abstract All the four individual isomers of β-methylphenylalanine have been synthesized in very high optical purities by utilizing in part the chiral imide enolate bromination methodology of Evans and co-workers.
Life Sciences | 1992
B. Búzás; Geza Toth; Silvia Cavagnero; V.J. Hruby; Anna Borsodi
A radiolabelled form of deltorphin II was synthesized by catalytic tritiation using [p-IPhe3]-deltorphin II as a precursor. The ligand labels rat brain membranes with a Kd value of 1.9 nM, and the Bmax was found to be 92 fmol/mg protein. This new tritiated ligand exhibits high affinity for the delta opioid binding site, whereas its binding to the mu type is weak and extremely low for the kappa type. Mu/delta and kappa/delta selectivity ratios were about 900 and 10,000, respectively. The highly delta selective binding properties of this new radioligand suggest that it could serve as an excellent tool for investigating the delta opioid receptors in various species.
Life Sciences | 1991
Thomas H. Kramer; Geza Toth; Ronald C. Haaseth; Terry O. Matsunaga; Peg Davis; Victor J. Hruby; Thomas F. Burks
Several peptides of diverse structure, reported to possess high affinity and selectivity for the delta opioid receptor, were studied using the mouse isolated vas deferens preparation to determine the effect of peptidase inhibition on their apparent potency. The peptides evaluated included [Leu5] enkephalin, the cyclic enkephalin analogs [D-Pen2,D-Pen5]enkephalin (DPDPE) and [D-Pen2,p-F-Phe4,D-Pen5]enkephalin (F-DPDPE), the linear enkephalin analogs [D-Ala2,D-Leu5]enkephalin (DADLE) and [D-Ser2(O-tBu), Leu5,Thr6]enkephalin (DSTBULET), and the naturally occurring amphibian peptides Tyr-D-Met-Phe-His-Leu-Met-Asp-NH2 (dermenkephalin), Tyr-D-Ala-Phe-Asp-Val-Val-Gly-NH2 (deltorphin I) and Tyr-D-Ala-Phe-Glu-Val-Val-Gly-NH2 (deltorphin II). Concentration-response curves were determined for each peptide in the absence and presence of a combination of the peptidase-inhibiting agents bacitracin, bestatin, and captopril. A wide range of potencies was observed, both in the control state and in the presence of peptidase inhibition. The synthetic enkephalin analogs demonstrated small increases in potency with peptidase inhibition (no increase in the case of DPDPE), whereas the naturally occurring peptides were markedly increased in potency, up to as much as 123-fold for dermenkephalin. In the presence of peptidase inhibition, deltorphin II was the most potent peptide tested (IC50 = 1.13 x 10(-10) molar), and as such is the most potent delta opioid agonist reported to date. Stability to metabolism must be considered in the design and evaluation of in vitro experiments using peptides of this type.
Biopolymers | 1996
Dirk Tourwé; K. Verschueren; Anne Frycia; Peg Davis; Frank Porreca; Victor J. Hruby; Geza Toth; Hendrika Jaspers; Patricia Verheyden; Georges Van Binst
Journal of Chromatography A | 1990
Geza Toth; Michal Lebl; Victor J. Hruby
International Journal of Peptide and Protein Research | 2009
Michal Lebl; Geza Toth; Jiřina Slaninová; Victor J. Hruby
Journal of Organic Chemistry | 1991
Shubh D. Sharma; Geza Toth; Victor J. Hruby
Archive | 1989
Victor J. Hruby; Geza Toth
Archive | 1991
Victor J. Hruby; Sunan Fang; Geza Toth; Ding Jiao; Terry O. Matsunaga; Nathan Collins; Richard J. Knapp; Henry I. Yamamura
Proceedings of the Western Pharmacology Society | 1989
Ayres Ea; Lemcke Pk; Thomas H. Kramer; Geza Toth; Hruby Vj; Thomas F. Burks