title: Toluene diisocyanate reactivity with glutathione across a vapor/liquid interface and subsequent transcarbamoylation of human albumin.
abstract: Glutathione has previously been identified as a reaction target for toluene diisocyanate (TDI) in vitro and in vivo, and has been suggested to contribute to toxic and allergic reactions to exposure. In this study, the reactivity of reduced glutathione (GSH) with TDI in vitro was further investigated using a mixed phase (vapor/liquid) exposure system to model the in vivo biophysics of exposure in the lower respiratory tract. HPLC/MS/MS was used to characterize the observed reaction products. Under the conditions tested, the major reaction products between TDI vapor and GSH were S-linked bis(GSH)-TDI and to a lesser extent mono(GSH)-TDI conjugates (with one N═C═O hydrolyzed). The vapor-phase-generated GSH-TDI conjugates were capable of transcarbamoylating human albumin in a pH-dependent manner, resulting in changes in the self-protein's conformation/charge, on the basis of electrophoretic mobility under native conditions. Specific sites of human albumin-TDI conjugation, mediated by GSH-TDI, were identified (Lys(73), Lys(159), Lys(190), Lys(199), Lys(212), Lys(351), Lys(136/137), Lys(413/414), and Lys(524/525)) along with overlap with those susceptible to direct conjugation by TDI. Together, the data extend the proof-of-principle for GSH to act as a "shuttle" for a reactive form of TDI, which could contribute to clinical responses to exposure.
authors.affiliation: Department of Internal Medicine, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06520-8057, USA. adam.wisnewski@yale.edu
authors.forename: Adam V
authors.initials: AV
authors.lastname: Wisnewski
authors.forename: Justin M
authors.initials: JM
authors.lastname: Hettick
authors.forename: Paul D
authors.initials: PD
authors.lastname: Siegel
mesh_terms: D000418:Albumins / Q000378:metabolism*; D000485:Allergens / Q000378:metabolism*; D002219:Carbamates / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D053719:Tandem Mass Spectrometry; D014051:Toluene 2,4-Diisocyanate / Q000378:metabolism*; D014835:Volatilization
chemical_list: D000418:Albumins; D000485:Allergens; D002219:Carbamates; D014051:Toluene 2,4-Diisocyanate; D005978:Glutathione; C070766:carbamic acid