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| Subject | Predicate | Object |
|---|---|---|
| http://purl.uniprot.org/citations/2398044 | http://www.w3.org/1999/02/22-rdf-syntax-ns#type | http://purl.uniprot.org/core/Journal_Citation |
| http://purl.uniprot.org/citations/2398044 | http://www.w3.org/1999/02/22-rdf-syntax-ns#type | http://purl.uniprot.org/core/Journal_Citation |
| http://purl.uniprot.org/citations/2398044 | http://www.w3.org/2000/01/rdf-schema#comment | "Three hemoglobins have been isolated from the symbiont-harboring gill of the bivalve mollusc Lucina pectinata. Oxyhemoglobin I (Hb I), which may be called sulfide-reactive hemoglobin, reacts with hydrogen sulfide to form ferric hemoglobin sulfide in a reaction that may proceed by nucleophilic displacement of bound superoxide anion by hydrosulfide anion. Hemoglobins II and II, called oxygen-reactive hemoglobins, remain oxygenated in the presence of hydrogen sulfide. Hemoglobin I is monomeric; Hb II and Hb III self-associate in a concentration-dependent manner and form a tetramer when mixed. Oxygen binding is not cooperative. Oxygen affinities are all nearly the same, P50 = 0.1 to 0.2 Torr, and are independent of pH. Combination of Hb I with oxygen is fast; k'on = (estimated) 100-200 x 10(6) M-1 s-1. Combination of Hb II and Hb III with oxygen is slow: k'on = 0.4 and 0.3 x 10(6) M-1 s-1, respectively. Dissociation of oxygen from Hb I is fast relative to myoglobin: koff = 61 s-1. Dissociation from Hb II and Hb III is slow: koff = 0.11 and 0.08 s-1, respectively. These large differences in rates of reaction together with differences in the reactions of carbon monoxide suggest differences in configuration of the distal heme pocket. The fast reactions of Hb I are comparable to those of hemoglobins that lack distal histidine residues. Slow dissociation of oxygen from Hb II and Hb III suggest that a distal residue may interact strongly with the bound ligand. We infer that Hb I may facilitate delivery of hydrogen sulfide to the chemoautotrophic bacterial symbiont and Hb II and Hb III may facilitate delivery of oxygen. The midpoint oxidation-reduction potential of the ferrous/ferric couple of Hb I, 103 +/-8 mV, was independent of pH. Potentials of Hb II and Hb III were pH-dependent. At neutral pH all three hemoglobins have similar midpoint potentials. The rate constant for combination of ferric Hb I with hydrogen sulfide increases 3000-fold from pH 10.5 to 5.5, with apparent pK 7.0, suggesting that undissociated hydrogen sulfide is the attacking ligand. At the acid limit combination of ferric Hb I with hydrogen sulfide, k'on = 2.3 x 10(5) M-1 s-1, is 40-fold faster than combination with ferric Hb II or myoglobin.(ABSTRACT TRUNCATED AT 400 WORDS)"xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.org/dc/terms/identifier | "doi:10.1016/s0021-9258(17)46185-0"xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.org/dc/terms/identifier | "doi:10.1016/s0021-9258(17)46185-0"xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/author | "Wittenberg J.B."xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/author | "Wittenberg J.B."xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/author | "Kraus D.W."xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/author | "Kraus D.W."xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/date | "1990"xsd:gYear |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/date | "1990"xsd:gYear |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/name | "J. Biol. Chem."xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/name | "J. Biol. Chem."xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/pages | "16043-16053"xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/pages | "16043-16053"xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/title | "Hemoglobins of the Lucina pectinata/bacteria symbiosis. I. Molecular properties, kinetics and equilibria of reactions with ligands."xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/title | "Hemoglobins of the Lucina pectinata/bacteria symbiosis. I. Molecular properties, kinetics and equilibria of reactions with ligands."xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/volume | "265"xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://purl.uniprot.org/core/volume | "265"xsd:string |
| http://purl.uniprot.org/citations/2398044 | http://www.w3.org/2004/02/skos/core#exactMatch | http://purl.uniprot.org/pubmed/2398044 |
| http://purl.uniprot.org/citations/2398044 | http://www.w3.org/2004/02/skos/core#exactMatch | http://purl.uniprot.org/pubmed/2398044 |
| http://purl.uniprot.org/citations/2398044 | http://xmlns.com/foaf/0.1/primaryTopicOf | https://pubmed.ncbi.nlm.nih.gov/2398044 |
| http://purl.uniprot.org/citations/2398044 | http://xmlns.com/foaf/0.1/primaryTopicOf | https://pubmed.ncbi.nlm.nih.gov/2398044 |
| http://purl.uniprot.org/uniprot/P41260 | http://purl.uniprot.org/core/citation | http://purl.uniprot.org/citations/2398044 |
| http://purl.uniprot.org/uniprot/P41262 | http://purl.uniprot.org/core/citation | http://purl.uniprot.org/citations/2398044 |