Measurement of hemoglobin and albumin adducts of tetrachlorobenzoquinone.
Tetrachloro-1,4-benzoquinone (Cl4BQ), a metabolite of pentachlorophenol (PCP), is believed to play a role in the genotoxicity of PCP. We have developed a method to measure the adducts of Cl4BQ with cysteine residues of hemoglobin (Hb) and albumin (Alb). This method employs the use of Raney nickel to selectively cleave the sulfur-bound adducts. Adducts of Hb and Alb with Cl4BQ were measured following modification of rat blood with Cl4BQ (0-90 microM) in vitro. The formation of both Hb and Alb adducts was linear over the entire range with second-order rate constants of 6.89 and 167 L mol-1 h-1, respectively. The proportions of the concentrations of these Hb and Alb adducts to those of all covalently-bound products were estimated to be 0.053 and 0.178, respectively, at initial Cl4BQ concentrations between 3 and 90 microM. The overall rate of reaction of Cl4BQ in rat blood (in vitro) was pseudo-first-order with an estimated half-time of 4.35 h. Hb and Alb adducts of Cl4BQ were also measured in vivo following oral administration of PCP to rats (0-20 mg/kg body wt). Linear production of Hb and Alb adducts was observed over the entire range of dosages, with slopes of 0.09 and 8.22 pmol of adduct (g of protein)-1 [(mg of PCP)/(kg body wt)]-1, respectively. On the basis of production of Hb adducts in vitro and in vivo, it is estimated that 2.7 x 10(-7) mol of Cl4BQ was released to the blood of rats per mole of PCP administered.(ABSTRACT TRUNCATED AT 250 WORDS)
Waidyanatha
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Department of Environmental Science and Engineering, School of Public Health, University of North Carolina at Chapel Hill 27599-7400.
McDonald
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Lin
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Rappaport
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D000418:Albumins / Q000737:chemistry*; D000818:Animals; D002703:Chloranil / Q000737:chemistry*; D002849:Chromatography, Gas; D003545:Cysteine / Q000737:chemistry; D004563:Electrochemistry; D008401:Gas Chromatography-Mass Spectrometry; D006454:Hemoglobins / Q000737:chemistry*; D066298:In Vitro Techniques; D008297:Male; D011485:Protein Binding; D051381:Rats; D011916:Rats, Inbred F344; D017207:Rats, Sprague-Dawley
D000418:Albumins; D006454:Hemoglobins; D002703:Chloranil; D003545:Cysteine