Identification of Lys190 as the primary binding site for pyridoxal 5'-phosphate in human serum albumin.
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).
Bohney
J P
JP
Department of Biochemistry, University of Louisville School of Medicine, KY 40292.
Fonda
M L
ML
Feldhoff
R C
RC
D000595:Amino Acid Sequence; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D008239:Lysine / Q000378:metabolism*; D008969:Molecular Sequence Data; D011732:Pyridoxal Phosphate / Q000378:metabolism*; D012709:Serum Albumin / Q000378:metabolism*
D012709:Serum Albumin; D011732:Pyridoxal Phosphate; D008239:Lysine