Properties of trout hemoglobins reconstituted with unnatural hemes.
Native globins isolated from trout hemoglobin compoents I and IV have been reconstituted with proto-, meso-, and deuteroheme, and the spectral and functional properties of the reconstituted hemoglobins have been investigated. Equilibrium and kinetic studies allow the following conclusions. (a) The properties of the proto-reconstituted hemoglobins are very similar, or indistinguishable, from those of the native Hb's I and IV. (B) The CO binding kinetics for both proteins were found to be consistent with the equilibrium data: the overall association rate constant increases (and the autocatalytic character of the reaction decreases) in the order proto, meso, deutero. (c) A marked pH dependence of both ligand affinity and cooperativity is maintained in the reconstituted Hb's IV: at pH 6 the fractional saturation with oxygen in air (Root effect) is lower for proto- than for meso- and deutero-Hb IV. The results obtained, including partial photodissociation experiments at different pH values, can be considered, to a first approximation, consistent with the basic features of a simple two-states model.
D000494:Allosteric Regulation; D000818:Animals; D002263:Carboxyhemoglobin / Q000378:metabolism; D006418:Heme / Q000031:analogs & derivatives; D006454:Hemoglobins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008024:Ligands; D010108:Oxyhemoglobins / Q000378:metabolism; D010782:Photolysis; D012487:Salmonidae / Q000097:blood*; D013329:Structure-Activity Relationship; D014337:Trout / Q000097:blood*
D006454:Hemoglobins; D008024:Ligands; D010108:Oxyhemoglobins; D006418:Heme; D002263:Carboxyhemoglobin