Synthesis of 5,5,6,6-D4-L-lysine-aflatoxin B1 for use as a mass spectrometric internal standard

Peter F. Scholl, John D. Groopman

Research output: Contribution to journalArticle

Abstract

Human exposure to the hepatocarcinogenic mycotoxin aflatoxin B1 results in modification of serum albumin lysine ε-amino residues to form lysine-aflatoxin adducts. A perdeuterated reference standard is now required to quantitatively measure this adduct in epidemiologic studies of liver cancer using isotopic dilution mass spectrometry. A convenient method for the preparation of D4-L-lysine-AFB1 using commercially available 5,5,6,6-D4-L-lysine is demonstrated for the first time. The application of two standard α-amino protection methods is also reported that simplifies the production of natural isotopic abundance lysine-AFB1 over the currently used method employing Nα-acetyl-L-lysine. t-Boc-Nα-lysine was used to prepare lysine-AFB1; however, a preferred method for directing reaction of AFB1-dialdehyde to the ε-amino group of 5,5,6,6-D4-L-lysine utilized cupric ions that were spontaneously removed during the reverse phase HPLC purification of D4-lysine-AFB1 using 1% HOAc. This strategy eliminates the need to otherwise synthesize and purify t-Boc-Nα- or N α-acetyl-5,5,6,6-D4-lysine and then TFA or enzymatically deprotect overnight to obtain the target compound.

Original languageEnglish (US)
Pages (from-to)807-815
Number of pages9
JournalJournal of Labelled Compounds and Radiopharmaceuticals
Volume47
Issue number11
DOIs
StatePublished - Oct 15 2004

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Keywords

  • Copper
  • D4-lysine
  • Isotope dilution mass spectrometry
  • Lysine-aflatoxin adduct
  • α-amino group protection

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Radiology Nuclear Medicine and imaging
  • Drug Discovery
  • Spectroscopy
  • Organic Chemistry

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