Diisopropylfluorophosphate-sensitive aryl acylamidase activity of fatty acid free human serum albumin

Indumathi Manoharan, Rathnam Boopathy

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Butyrylcholinesterase in human plasma and acetylcholinesterase in human red blood cells have aryl acylamidase activity toward o-nitroacetanilide, hydrolyzing the amide bond to produce o-nitroaniline and acetate. People with a genetic variant of butyrylcholinesterase that had no detectable activity with butyrylthiocholine, nevertheless had aryl acylamidase activity in their plasma. To determine the source of this aryl acylamidase activity we tested fatty acid free human albumin for activity. We found that albumin had aryl acylacylamidase activity and that this activity was inhibited by diisopropylfluorophosphate. Since the esterase activity of albumin is also inhibited by diisopropylfluorophosphate, and since it is known that diisopropylfluorophosphate covalently binds to Tyr 411 of human albumin, we conclude that the active site for aryl acylamidase activity of albumin is Tyr 411. Albumin accounts for about 10% of the aryl acylamidase activity in human plasma.

Original languageEnglish (US)
Pages (from-to)186-188
Number of pages3
JournalArchives of Biochemistry and Biophysics
Issue number2
StatePublished - Aug 15 2006
Externally publishedYes


  • Albumin
  • Aryl acylamidase
  • Silent butyrylcholinesterase
  • Tyr 411

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology


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