Structure of pyridoxal kinase from sheep brain and role of the tryptophanyl residues

Bruno Maras, Sofia Valiante, Stefania Orru, Maurizio Simmaco, Donatella Barra, Jorge E. Churchich

Research output: Contribution to journalArticlepeer-review


The primary structure of sheep brain pyridoxal kinase has been determined by direct chemical and physical methods. The enzyme contains 312 amino acid residues with an acetylated methionine at the N-terminus, yielding a molecular mass of 34,861 Da. The functional role played by the two tryptophanyl residues in positions 52 and 244 of the polypeptide chain has been investigated by fluorescence spectroscopy. The tryptophanyl residues are not completely exposed to the rapidly relaxing solvent and they are poorly accessible to collisional quenchers. Chemical modification with NBS abolishes the catalytic activity of the kinase. The amino acid sequence of the sheep brain enzyme shows high similarity (86.2% identity) with the human pyridoxal kinase recently reported [Hanna, Turner, and Kirkness, (1997), J. Biol. Chem. 272, 10756-10760]. Comparison of the mammalian proteins with bacterial and yeast putative pyridoxal kinases retrieved from the Swiss-Prot data bank shows a low degree of overall similarity. In particular, the putative ATP-binding domain is conserved, whereas the region that appears to be crucial in the binding of the pyridoxal substrate is not. Thus, the assignment of the bacterial and yeast cDN A-deduced proteins as pyridoxal kinases should be taken with caution.

Original languageEnglish
Pages (from-to)259-268
Number of pages10
JournalProtein Journal
Issue number3
Publication statusPublished - 1999


  • Active site
  • Fluorescence
  • Pyridoxal kinase
  • Sequence

ASJC Scopus subject areas

  • Biochemistry
  • Bioengineering
  • Analytical Chemistry
  • Organic Chemistry


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