title: Molecular controls of the oxygenation and redox reactions of hemoglobin.
abstract: CONCLUSIONS
  The broad classes of O(2)-binding proteins known as hemoglobins (Hbs) carry out oxygenation and redox functions that allow organisms with significantly different physiological demands to exist in a wide range of environments. This is aided by allosteric controls that modulate the protein's redox reactions as well as its O(2)-binding functions.
  
  
  BACKGROUND
  The controls of Hb's redox reactions can differ appreciably from the molecular controls for Hb oxygenation and come into play in elegant mechanisms for dealing with nitrosative stress, in the malarial resistance conferred by sickle cell Hb, and in the as-yet unsuccessful designs for safe and effective blood substitutes.
  
  
  RESULTS
  An important basic principle in consideration of Hb's redox reactions is the distinction between kinetic and thermodynamic reaction control. Clarification of these modes of control is critical to gaining an increased understanding of Hb-mediated oxidative processes and oxidative toxicity in vivo.
  
  
  CONCLUSIONS
  This review addresses emerging concepts and some unresolved questions regarding the interplay between the oxygenation and oxidation reactions of structurally diverse Hbs, both within red blood cells and under acellular conditions. Developing methods that control Hb-mediated oxidative toxicity will be critical to the future development of Hb-based blood substitutes.
authors.affiliation: Nicholas School of the Environment, Duke University Marine Laboratory, Beaufort, NC 28516, USA. bona@duke.edu
authors.forename: Celia
authors.initials: C
authors.lastname: Bonaventura
authors.forename: Robert
authors.initials: R
authors.lastname: Henkens
authors.forename: Abdu I
authors.initials: AI
authors.lastname: Alayash
authors.forename: Sambuddha
authors.initials: S
authors.lastname: Banerjee
authors.forename: Alvin L
authors.initials: AL
authors.lastname: Crumbliss
mesh_terms: D000818:Animals; D001802:Blood Substitutes / Q000737:chemistry / Q000378:metabolism; D006454:Hemoglobins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D010084:Oxidation-Reduction; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D011485:Protein Binding
chemical_list: D001802:Blood Substitutes; D006454:Hemoglobins; D010100:Oxygen