tailieunhanh - Báo cáo khoa học: Identification and characterization of oxidized human serum albumin A slight structural change impairs its ligand-binding and antioxidant functions

Human serum albumin (HSA) exists in both reduced and oxidized forms, and the percentage of oxidized albumin increases in several diseases. How-ever, little is known regarding the pathophysiological significance of oxida-tion due to poor characterization of the precise structural and functional properties of oxidized HSA. | iFEBS Journal Identification and characterization of oxidized human serum albumin A slight structural change impairs its ligand-binding and antioxidant functions A IZ I 1 IS I IS I 2. Al I xz I 2 I I 1 2 ts 1 I I 1 Asami Kawakami Kazuyuki Kubota Naoyuki Yamada Uno Tagami Kenji Takehana Ichiro Sonaka1 Eiichiro Suzuki2 and Kazuo Hirayama2 1 PharmaceuticalResearch Laboratories Ajinomoto Co. Inc. Kawasaki Japan 2 Institute of Life Science Ajinomoto Co. Inc. Kawasaki Japan Keywords human serum albumin mercaptoalbumin nonmercaptoalbumin ESI-TOFMS oxidation Correspondence K. Takehana Pharmaceutical Research Laboratories Ajinomoto Co. Inc. 1-1 Suzuki-cho Kawasaki-ku Kawasaki 210-8681 Japan Fax 81 44 2105871 Tel 81 44 2105822 E-mail kenji_takehana@ These authors contributed equally to this work Received 26 April2006 accepted 25 May 2006 Human serum albumin HSA exists in both reduced and oxidized forms and the percentage of oxidized albumin increases in several diseases. However little is known regarding the pathophysiological significance of oxidation due to poor characterization of the precise structural and functional properties of oxidized HSA. Here we characterize both the structural and functional differences between reduced and oxidized HSA. Using LC-ESI-TOFMS and FTMS analysis we determined that the major structural change in oxidized HSA in healthy human plasma is a disulfide-bonded cysteine at the thiol of Cys34 of reduced HSA. Based on this structural information we prepared standard samples of purified HSA . nonoxidized intact purified HSA which mainly exists in reduced form mildly oxidized and highly oxidized HSA. Using these standards we demonstrated several differences in functional properties of HSA including protease susceptibility ligand-binding affinity and antioxidant activity. From these observations we conclude that an increased level of oxidized HSA may impair HSA function in a number of pathological conditions. doi .