title: The modification of hemoglobin by citrate.
abstract: Citrate, when activated by a water-soluble carbodiimide, covalently modifies hemoglobin. At pH values near neutrality, complete modification of the N-terminal valine residues of alpha- and beta-globin chains can be accomplished with a high degree of specificity. These groups react at a much more rapid rate than a slower reacting set of functional groups. Modification of hemoglobin with citrate alters the oxygen affinity of the protein. Although the p50 is not changed, the cooperative nature of oxygen binding is greatly decreased. Hemoglobin S modified with citrate is more soluble than unmodified hemoglobin S. The time taken for deoxygenated hemoglobin S to come out of solution in concentrated phosphate solutions is increased by citrate modification.
authors.affiliation: Department of Biochemistry, University of Ottawa, Ontario, Canada.
authors.forename: P J
authors.initials: PJ
authors.lastname: Anderson
mesh_terms: D002848:Chromatography, DEAE-Cellulose; D002951:Citrates / Q000737:chemistry*; D005022:Ethyldimethylaminopropyl Carbodiimide / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D010100:Oxygen / Q000378:metabolism; D009764:o-Phthalaldehyde / Q000737:chemistry
chemical_list: D002951:Citrates; D006454:Hemoglobins; D009764:o-Phthalaldehyde; D005022:Ethyldimethylaminopropyl Carbodiimide; D010100:Oxygen