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Identification of Lys 190 as the primary binding site for pyridoxal 5′‐phosphate in human serum albumin
Author(s) -
Bohney James P.,
Fonda Margaret L.,
Feldhoff Richard C.
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80073-p
Subject(s) - chemistry , human serum albumin , biochemistry , peptide , binding site , pyridoxal phosphate , covalent bond , pyridoxal , stereochemistry , serum albumin , cofactor , phosphate , enzyme , organic chemistry
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 [ 3 H]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 Lys 190 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 (Lys 325 ) and acetylation by aspirin (Lys 199 ).