Biochemical evidence that Escherichia coli hyi (orf b0508, gip) gene encodes hydroxypyruvate isomerase

Biochim Biophys Acta. 1999 Nov 16;1435(1-2):153-9. doi: 10.1016/s0167-4838(99)00216-2.


We found a significant activity of hydroxypyruvate isomerase in Escherichia coli clone cells harboring an E. coli gene (called orf b0508 or gip), which is located downstream of the glyoxylate carboligase gene. We newly designated the gene hyi. The enzyme was purified from cell extracts of the E. coli clone. The enzyme had a molecular mass of 58 kDa and was composed of two identical subunits. The optimum pH for the isomerization of hydroxypyruvate was 6.8-7.2. The enzyme required no cofactor. It exclusively catalyzed the isomerization between hydroxypyruvate and tartronate semialdehyde. The apparent K(m) value for hydroxypyruvate was 12.5 mM. The amino acid sequence of E. coli hydroxypyruvate isomerase is highly similar to those of glyoxylate-induced proteins, Gip, found widely from prokaryotes to eukaryotes.

MeSH terms

  • Aldose-Ketose Isomerases / chemistry
  • Aldose-Ketose Isomerases / genetics*
  • Aldose-Ketose Isomerases / isolation & purification
  • Amino Acid Sequence
  • Cell Extracts
  • Escherichia coli / enzymology
  • Escherichia coli / genetics*
  • Escherichia coli Proteins*
  • Genes, Bacterial*
  • Molecular Sequence Data
  • Sequence Alignment
  • Spectrophotometry, Ultraviolet


  • Cell Extracts
  • Escherichia coli Proteins
  • Aldose-Ketose Isomerases
  • hyi protein, E coli

Associated data

  • GENBANK/AB028043