title: Haptoglobin preferentially binds β but not α subunits cross-linked hemoglobin tetramers with minimal effects on ligand and redox reactions.
abstract: Human hemoglobin (Hb) and haptoglobin (Hp) exhibit an extremely high affinity for each other, and the dissociation of Hb tetramers into dimers is generally believed to be a prerequisite for complex formation. We have investigated Hp interactions with native Hb, αα, and ββ cross-linked Hb (ααXLHb and ββXLHb, respectively), and rapid kinetics of Hb ligand binding as well as the redox reactivity in the presence of and absence of Hp. The quaternary conformation of ββ subunit cross-linking results in a higher binding affinity than that of αα subunit cross-linked Hb. However, ββ cross-linked Hb exhibits a four fold slower association rate constant than the reaction rate of unmodified Hb with Hp. The Hp contact regions in the Hb dimer interfaces appear to be more readily exposed in ββXLHb than ααXLHb. In addition, apart from the functional changes caused by chemical modifications, Hp binding does not induce appreciable effects on the ligand binding and redox reactions of ββXLHb. Our findings may therefore be relevant to the design of safer Hb-based oxygen therapeutics by utilizing this preferential binding of ββXLHb to Hp. This may ultimately provide a safe oxidative inactivation and clearance pathway for chemically modified Hbs in circulation.
authors.affiliation: Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland, United States of America. yiping.jia@fda.hhs.gov
authors.forename: Yiping
authors.initials: Y
authors.lastname: Jia
authors.forename: Francine
authors.initials: F
authors.lastname: Wood
authors.forename: Paul W
authors.initials: PW
authors.lastname: Buehler
authors.forename: Abdu I
authors.initials: AI
authors.lastname: Alayash
mesh_terms: D002851:Chromatography, High Pressure Liquid; D006242:Haptoglobins / Q000737:chemistry*; D006454:Hemoglobins / Q000737:chemistry*; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D008024:Ligands; D009573:Nitrites / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D013050:Spectrometry, Fluorescence
chemical_list: D006242:Haptoglobins; D006454:Hemoglobins; D008024:Ligands; D009573:Nitrites; D006861:Hydrogen Peroxide; D010100:Oxygen
references.citation: Biochim Biophys Acta. 2004 Jun 11;1672(3):164-73
references.pmid: 15182936
references.citation: Biochemistry. 1979 Oct 2;18(20):4265-70
references.pmid: 486423
references.citation: J Biol Chem. 1978 Apr 10;253(7):2386-91
references.pmid: 204647
references.citation: Biochemistry. 2002 Jun 11;41(23):7407-15
references.pmid: 12044174
references.citation: Biochemistry. 1973 Sep 11;12(19):3744-51
references.pmid: 4788311
references.citation: J Biol Chem. 1989 Apr 15;264(11):6191-5
references.pmid: 2495279
references.citation: Nature. 2012 Sep 20;489(7416):456-9
references.pmid: 22922649
references.citation: J Biol Chem. 1991 Sep 15;266(26):17049-59
references.pmid: 1910038
references.citation: Biochemistry. 1982 Nov 9;21(23):5901-9
references.pmid: 6817783
references.citation: Clin Chim Acta. 2011 Mar 18;412(7-8):493-8
references.pmid: 21159311
references.citation: J Biol Chem. 1991 Dec 5;266(34):23033-40
references.pmid: 1744099
references.citation: J Biol Chem. 2007 Jan 12;282(2):1072-9
references.pmid: 17102136
references.citation: J Mol Biol. 1968 Jul 14;34(2):347-56
references.pmid: 5760461
references.citation: J Biol Chem. 1980 Apr 10;255(7):3038-41
references.pmid: 7358726
references.citation: Nitric Oxide. 2012 Jun 30;27(1):32-9
references.pmid: 22521791
references.citation: Free Radic Biol Med. 2012 Sep 15;53(6):1317-26
references.pmid: 22841869
references.citation: Biochim Biophys Acta. 2010 Oct;1804(10):1988-95
references.pmid: 20601225
references.citation: Antioxid Redox Signal. 2013 Jun 10;18(17):2264-73
references.pmid: 22702311
references.citation: Biochim Biophys Acta. 1982 Apr 3;702(2):237-41
references.pmid: 6282334
references.citation: J Biol Chem. 1999 Jan 22;274(4):2029-37
references.pmid: 9890961
references.citation: Biologicals. 1997 Sep;25(3):257-68
references.pmid: 9324994
references.citation: J Biol Chem. 1971 Jan 10;246(1):69-73
references.pmid: 5541775
references.citation: Antioxid Redox Signal. 2010 Feb;12(2):293-304
references.pmid: 19659435
references.citation: Blood. 2009 Mar 12;113(11):2578-86
references.pmid: 19131549
references.citation: Proc Natl Acad Sci U S A. 1987 Oct;84(20):7280-4
references.pmid: 3478694
references.citation: Antioxid Redox Signal. 2008 Aug;10(8):1449-62
references.pmid: 18522492
references.citation: FEBS J. 2008 Nov;275(22):5648-56
references.pmid: 18959750
references.citation: J Biol Chem. 2007 Feb 16;282(7):4894-4907
references.pmid: 17178725
references.citation: J Biol Chem. 1989 Oct 25;264(30):17824-33
references.pmid: 2808353
references.citation: J Leukoc Biol. 2007 Jul;82(1):106-10
references.pmid: 17460152
references.citation: J Clin Invest. 2009 Aug;119(8):2271-80
references.pmid: 19620788
references.citation: Biochim Biophys Acta. 1982 Dec 20;709(2):187-93
references.pmid: 6295490
references.citation: Free Radic Biol Med. 1998 Jun;24(9):1535-6
references.pmid: 9641272
references.citation: J Biol Chem. 1976 Jan 25;251(2):465-70
references.pmid: 1245483
references.citation: Nature. 2001 Jan 11;409(6817):198-201
references.pmid: 11196644
references.citation: J Biol Chem. 1981 Jan 25;256(2):672-9
references.pmid: 7451467