Identification of Lys190 as the primary binding site for pyridoxal 5'-phosphate in human serum albumin

FEBS Lett. 1992 Feb 24;298(2-3):266-8. doi: 10.1016/0014-5793(92)80073-p.


The covalent binding of pyridoxal 5'-phosphate (PLP) to human serum albumin (HSA) is important in the regulation of PLP metabolism. In plasma, PLP is bound to HSA at a single high-affinity and at two or more nonspecific sites. To characterize the primary PLP binding site, HSA was incubated with [3H] PLP, and the Schiff base linkage was reduced with potassium borohydride. Tryptic peptides were purified, and the major labeled peptide was sequenced. Amino acid analysis confirmed a homogeneous peptide Leu-Asp-Glu-Leu-Arg-Asp-Glu-Gly-Xaa-Ala-Ser-Ser-Ala-Lys which corresponds to residues 182-195 of HSA. The data indicate that Lys190 is the primary PLP binding site. This Lys residue is distinct from other sites of covalent adduct formation; namely, the primary sites for nonenzymatic glycosylation (Lys525) and acetylation by aspirin (Lys199).

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Chromatography, High Pressure Liquid
  • Humans
  • Lysine / metabolism*
  • Molecular Sequence Data
  • Pyridoxal Phosphate / metabolism*
  • Serum Albumin / metabolism*


  • Serum Albumin
  • Pyridoxal Phosphate
  • Lysine