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Quantitative evaluation of the role of cysteine and methionine residues in the antioxidant activity of human serum albumin using recombinant mutants
Author(s) -
Iwao Yasunori,
Ishima Yu,
Yamada Junji,
Noguchi Taishi,
KraghHansen Ulrich,
Mera Katsumi,
Honda Daisuke,
Suenaga Ayaka,
Maruyama Toru,
Otagiri Masaki
Publication year - 2012
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1002/iub.567
Subject(s) - cysteine , recombinant dna , methionine , biochemistry , chemistry , mutant , human serum albumin , albumin , antioxidant , glutathione , amino acid , enzyme , gene
The importance of cysteine (Cys) and methionine (Met) residues for the antioxidant activity of human serum albumin (HSA) was investigated using recombinant HSA mutants, in which Cys34 and/or the six Met residues had been mutated to Ala. The scavenging activities of the mutants against five reactive oxygen and nitrogen species were evaluated by a chemiluminescence assay, electron paramagnetic resonance spectroscopy, or a HPLC‐flow reactor assay. Our results showed that the contributions of Cys34 and the Met residues to the antioxidant activity of HSA were 61% and 29% against O 2 •− , 68% and 61% against H 2 O 2 , 38% and 6% against HO • , 36% and 13% against HOCl, and 51% and 1% against • NO, respectively. Thus, the findings propose in a direct way that Cys34 plays a more important role than the Met residues in the antioxidant activity of HSA. © 2012 IUBMB Life, 2012