Carbon Disulfide and N,N-Diethyldithiocarbamate Generate Thiourea Cross-Links on Erythrocyte Spectrin in Vivo

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• 作者：John C. L. Erve ; Venkataraman Amarnath ; Doyle G. Graham ; Robert C. Sills ; A. L. Morgan ; and William M. Valentine
• 刊名：Chemical Research in Toxicology
• 出版年：1998
• 出版时间：May 1998
• 年：1998
• 卷：11
• 期：5
• 页码：544 - 549
• 全文大小：87K
• 年卷期：v.11,no.5(May 1998)
• ISSN：1520-5010

文摘

CS₂, a known neurotoxicant, is used in theviscose production of rayon and is also adecomposition product ofN,N-diethyldithiocarbamate, a metabolic productof the drugdisulfiram used in alcohol aversion therapy. Previous in vitroinvestigations have demonstratedthe ability of CS₂ to cross-link proteins through thiourea,dithiocarbamate ester, and disulfidestructures. Although in vivo studies have supported proteincross-linking as both a mechanismof neurotoxicity and a potential biomarker of effect, the chemicalstructures responsible forCS₂-mediated protein cross-linking in vivo have not beenelucidated. In the present study,the structure of one type of stable protein cross-link produced onerythrocyte spectrin by CS₂in vivo is determined. Rats were exposed to 50, 500, and 800 ppmCS₂ for 13 weeks byinhalation or to 3 mmol/kgN,N-diethyldithiocarbamate administered orally onalternatingdays for 8 weeks. Erythrocyte spectrin preparations from controland exposed rats werehydrolyzed using 6 N HCl and separated by size-exclusionchromatography. The fraction thatcoeluted with the synthetic deuterated lysine-lysine thiourea internalstandard was derivatizedwith3-[4'-[(N,N,N-trimethylamino)ethylene]phenyl]2-isothiocyanate and analyzed by liquidchromatography tandem mass spectrometry using selected reactionmonitoring detection.Lysine-lysine thiourea was detected in spectrin preparationsobtained from CS₂-treated ratsat 500 and 800 ppm andN,N-diethyldithiocarbamate-treated rats, but notfrom controls. Theseresults establish that CS₂-mediated protein cross-linkingoccurs in vivo through the generationof Lys-Lys thiourea and that diethyldithiocarbamate can, through invivo release of CS₂, producethe same cross-linking structure. This observation supports theutility of cross-linking ofperipheral proteins as a specific dosimeter of internal exposure forCS₂ and provides amechanistic explanation to account for the high-molecular-weightneurofilament protein speciesisolated from rats exposed to CS₂ orN,N-diethyldithiocarbamate.