Cisplatin was shown to strongly inhibit the decatenation and relaxation activity of isolated human DNA topoisomerase IIalpha. This inhibition was not accompanied by stabilization of a covalent topoisomerase IIalpha-DNA intermediate. Pretreatment of kinetoplast plasmid DNA (kDNA) or pBR322 DNA with submicromolar concentrations of cisplatin quickly rendered these substrates incompetent in the top...

Acrylamide (ACR) is a conjugated type-2 alkene that produces synaptic toxicity presumably by sulfhydryl adduction. The alpha,beta-unsaturated carbonyl of ACR is a soft electrophile and, therefore, adduction of nucleophilic thiol groups could occur through a conjugate (Michael) addition reaction. To address the mechanism of thiol adduct formation and corresponding neurotoxicological importance, ...

Williamson, W. T. (North Carolina State of the University of North Carolina, Raleigh), S. B. Tove, and M. L. Speck. Extracellular proteinase of Streptococcus lactis. J. Bacteriol. 87:49-53. 1964.-Streptococcus lactis was shown to produce an extracellular proteolytic enzyme(s). A 120-fold purification of the proteinase was obtained from the cell-free culture medium by ammonium sulfate fractionat...

Chronic, low level exposure to toxic metals is an increasing global problem. The symptoms associated with the slow accumulation of toxic metals are multiple and rather nondescript, and overt expression of toxic effects may not appear until later in life. The sulfhydryl-reactive metals (mercury, cadmium, lead, arsenic) are particularly insidious and can affect a vast array of biochemical and nut...

We demonstrate kinetically that the reaction of 5,5V-dithiobis(2-nitrobenzoate) with the CysF9[93]h sulfhydryl group of domestic cat hemoglobins is a reversible process. In the major hemoglobin, in which the NH3 + terminal group of GlyNA1[1]h is free, kf, the apparent forward second order rate constant, has a complex pH dependence profile. In the minor hemoglobin, the NH3 + terminal group of Se...

Aminoglycoside antibiotics such as gentamicin have long been known to destroy cochlear and vestibular hair cells in vivo. In the cochlea outer hair cells are preferentially affected. In contrast, gentamicin will not damage outer hair cells in vitro unless it has been enzymatically converted to a cytotoxic metabolite. Several potential inhibitors of this enzymatic reaction were tested in an in v...

The rates at which the sulfhydryl groups on each chain of hemoglobin fi4 react with N-ethylmaleimide and iodoacetate have been measured. The sulfhydryl group at position 93 reacts with both alkylating agents at approximately the same rate as normal liganded hemoglobin. The sulfhydryl group at position 112, which is not available in normal hemoglobin, reacts in hemoglobin f14 and does so much mo...

The in vivo effect of trimethyltin chloride (Me(3)SnCl), free base meso-tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)porphyrin (R'(4)PH(2)) and their equimolar mixture, on the enzymatic activity of catalase (CAT), superoxide dismutase (SOD), and on the total content of free sulfhydryl groups has been studied in rat liver and kidney. It was demonstrated that the simultaneous treatment of tested an...