Richard J. O'Connor

One-dimensional and two-dimensional nuclear magnetic resonance studies of the reaction of phenyldichloroarsine with glutathione

14C-labeled phenyldichloroarsine (PDA) enters the red blood cell and forms a 1:2 adduct with intracellular glutathione. Upon gel filtration of the hemolysate, [14C]PDA was recovered with the glutathione-containing fractions. One-dimensional and two-dimensional nuclear magnetic resonance spectroscopy were used to confirm the structure of the adduct and elucidate its stereochemistry, stability, and reactivity.

Regeneration of functional hemoglobin from iron(III) hemoglobin by reduction with hydrogen and a heterogeneous catalyst

Functional hemoglobin was regenerated from partially autoxidized hemoglobin by reduction with molecular hydrogen in the presence of a heterogeneous catalyst consisting of elemental platinum embedded in an electroactive polymer. The visible spectrum of the regenerated hemoglobin was identical to that of native iron(II) hemoglobin. The regenerated hemoglobin displayed highly cooperative oxygen-binding characteristics. P50 values for oxidized-regenerated hemoglobin samples were not different from native hemoglobin. The Hill coefficients for regenerated hemoglobin were slightly lower than the controls, possibly because of small amounts of irreversibly oxidized hemoglobin arising during the initial autoxidation. The advantages of the reduction system include: (1) the heterogeneous catalyst avoids the problem of protein adsorption onto bare platinum, (2) catalyst and reducing agent are easily removed from the protein, and (3) the by-product H+ is buffered easily.

Reaction of cysteine(s) with phenyldichloroarsine

Abstract : In order to further our studies dealing with the interaction of organic arsenicals with biological sulfhydryl-containing molecules, we investigated the reaction of phenyldichloroarsine with L-cysteine, and two derivatives of L-cysteine in methanol-d4. We found that cysteine (in contrast to glutathione in H2O) formed a mono-cysteine adduct when the L-Cys/PDA ratio was < or = 1:1 (2). When cysteine was present in two molar equivalents, the expected 2:1 adduct was formed via chelation of the two sulfur atoms of cysteine to the arsenic atom (3). Both L-cysteine methyl ester and N-acetyl-L-cysteine reacted like L-cysteine and formed a 1:1 adduct when the ratio was < or =. (jg)

Preparation, structure, and solution dynamics of phenyldichloroarsine-thio sugar adducts

In order to study the interactions betwen trivalent organic arsenicals and biologically relevant molecules, we investigated the structure and solution dynamics of the 1:2 adducts formed between phenyldichloroarsine (PDA) and the two thio sugars, 1-thio-β-D-glucopyranose and 1-thio-β-D-galactopyranose

Reaction of trans-2-Chlorovinylarsine Oxide with Polydeoxynucleotides

Trans-2-chlorovinylarsine oxide (in DCl/acetone-d6) was added to various polydeoxynucleotides. The arsenical did react with poly[dG].poly[dC], releasing guanine, and resulting in a partial apurinic duplex.