A new assay for albumin and hemoglobin adducts of 1,2- and 1,4-benzoquinones

Chem Biol Interact. 1998 Sep 4;115(2):117-39. doi: 10.1016/s0009-2797(98)00067-2.

Abstract

A new method has been developed to detect mono-S-substituted cysteinyl adducts of 1,2- and 1,4-benzoquinone (BQ) in hemoglobin (Hb) and albumin (Alb). After reacting the protein with trifluoroacetic anhydride and methanesulfonic acid, the resulting isomers of O,O',S-tris-trifluoroacetyl-hydroquinone and -catechol are extracted and detected by gas-chromatography-mass spectrometry in the negative-ion chemical ionization mode. The limit of detection of the assay is about 20 pmol adduct/g protein. This assay was employed to quantitate mono-S-substituted background adducts in human and rat Hb and Alb and benzene-specific adducts in Hb and Alb from F344 rats following a single oral dosage of 50-400 mg [13C6]benzene/kg body wt. In Alb, a dose-related increase in both [13C6]1,2- and [13C6]1,4-BQ adducts was observed with [[13C6]]1,4-BQ-Alb] >> [[13C6]1,2-BQ-Alb]. The formation of [13C6]1,2-BQ-Alb was linear with increasing dosage of benzene with a slope of 2.3 (pmol adduct/g protein)/(mg/kg body wt.) (S.E. = 0.18, R2 = 0.91). However, at dosages above about 100 mg [13C6]benzene/kg body wt., the levels of 1,4-BQ-Alb were greater than proportional to the dosage. Mono-S-substituted adducts of [13C6]1,2-BQ and [13C6]1,4-BQ were not detected in Hb. The background ([12C6]) adducts of 1,2- and 1,4-BQ in 20 F344 rats were estimated (in nmol adduct/g of protein) to be 3.9 (S.E. = 0.23) and 4.9 (S.E. = 0.30) in Hb and 2.7 (S.E. = 0.24) and 11.4 (S.E. = 0.60) in Alb. At the highest dosage of 400 mg [13C6]benzene/kg body wt., background levels of 1,2-BQ-Alb were about 4-fold higher than those of the benzene-specific adducts whereas the benzene-specific levels of 1,4-BQ-Alb were about 7-fold higher than those of the background adducts. Background levels of 1,2- and 1,4-BQ adducts in 10 portions of commercial human proteins were found to be (in nmol adduct/g of protein) 1.6 (S.E. = 0.05) and 0.85 (S.E. = 0.04) in Hb and 1.6 (S.E. = 0.06) and 8.9 (S.E. = 0.36) in Alb.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetic Anhydrides
  • Animals
  • Benzene / chemistry
  • Benzene / toxicity
  • Benzoquinones / analysis*
  • Carcinogens / chemistry
  • Carcinogens / toxicity
  • Cyclohexanes / analysis
  • Fluoroacetates
  • Gas Chromatography-Mass Spectrometry
  • Hemoglobins / analysis
  • Hemoglobins / chemistry*
  • Humans
  • Male
  • Mesylates
  • Rats
  • Rats, Inbred F344
  • Serum Albumin / analysis
  • Serum Albumin / chemistry*

Substances

  • Acetic Anhydrides
  • Benzoquinones
  • Carcinogens
  • Cyclohexanes
  • Fluoroacetates
  • Hemoglobins
  • Mesylates
  • Serum Albumin
  • methanesulfonic acid
  • quinone
  • trifluoroacetic anhydride
  • Benzene
  • 2-benzoquinone
  • benzene oxide