Biosynthesis of vitamin B6: direct identification of the product of the PdxA-catalyzed oxidation of 4-hydroxy-l-threonine-4-phosphate using electrospray ionization mass spectrometry

Bioorg Med Chem Lett. 2004 Apr 5;14(7):1633-6. doi: 10.1016/j.bmcl.2004.01.065.

Abstract

PdxA (E.C. 1.1.1.262) catalyzes a key step in the biosynthesis of vitamin B(6): the nicotinamide-dependent oxidation of 4-hydroxy-l-threonine-4-phosphate (HTP) to a product tentatively identified as 3-amino-1-hydroxyacetone 1-phosphate (AHAP). To date, the evidence for the formation of AHAP, while self-consistent, has been largely circumstantial, and does not exclude the possibility that the actual product of the enzyme-catalyzed oxidation of HTP might be 2-amino-3-oxo-4-hydroxybutyric acid 4-phosphate which could undergo rapid, non-enzyme-catalyzed decarboxylation once released from the protein. Use of negative ion electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometric analysis (MS-MS) confirms that AHAP is the product of the PdxA-catalyzed reaction.

Publication types

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

MeSH terms

  • Catalysis
  • Escherichia coli Proteins / analysis*
  • Escherichia coli Proteins / metabolism
  • Oxidation-Reduction
  • Oxidoreductases / analysis*
  • Oxidoreductases / metabolism
  • Phosphothreonine / analysis*
  • Phosphothreonine / metabolism
  • Spectrometry, Mass, Electrospray Ionization / methods*
  • Vitamin B 6 / analysis*
  • Vitamin B 6 / biosynthesis*

Substances

  • Escherichia coli Proteins
  • Phosphothreonine
  • pdxA protein, E coli
  • Vitamin B 6
  • Oxidoreductases