ArticleThe Journal of biological chemistry2010
Distal histidine stabilizes bound O2 and acts as a gate for ligand entry in both subunits of adult human hemoglobin.
Article in The Journal of biological chemistry, 2010. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 51 papers.
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51 citing papers in PubMed, 112 citations in OpenAlex.
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- Global Environmental Factors Impact the Evolution of Adult Hemoglobins in Squamata Reptiles (Lizards and Snakes) and Terrestrial Turtles.Genome biology and evolution · 2025Article
- Direct observation of two-channel photodissociation of carbon monoxide from the hemoglobin subunits.Nature communications · 2025Article
- Rational design of tertiary coordination sphere of a heme-based sensor for two-orders enhanced oxygen affinity.bioRxiv : the preprint server for biology · 2025Article
- Structural and clinical characterization of Hb Móstoles (HBA2:c.176A>G; p.His59Arg): a new unstable alpha-globin variant with thalassemic features.American journal of blood research · 2025Article
- (4-(Adamantan-1-yl)-1-(isopropyl)-1Molbank · 2023Article
- The Aer2 chemoreceptor from Vibrio vulnificus is a tri-PAS-heme oxygen sensor.Molecular microbiology · 2023Article
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- Oxidative Implications of Substituting a Conserved Cysteine Residue in Sugar Beet Phytoglobin BvPgb 1.2.Antioxidants (Basel, Switzerland) · 2022Article
- Kinetic mechanisms for OMolecular aspects of medicine · 2022Review
- Towards understanding non-equivalence of α and β subunits within human hemoglobin in conformational relaxation and molecular oxygen rebinding.Chemical science · 2021Article
- Thermal denaturation and autoxidation profiles of carangid fish myoglobins.Fish physiology and biochemistry · 2021Article
- Article
- Atomistic Simulations of Heme Dissociation Pathways in Human Methemoglobins Reveal Hidden Intermediates.Biochemistry · 2020Article
- Regulation of Nitric Oxide Metabolism and Vascular Tone by Cytoglobin.Antioxidants & redox signaling · 2020Review
- Impact of azole drugs on energetics, kinetics, and ligand migration pathways of CO photo-dissociation in bacterial flavohemoglobins.RSC advances · 2020Article
- The Interplay between Molten Globules and Heme Disassociation Defines Human Hemoglobin Disassembly.Biophysical journal · 2020Article
- Lessons Learned from 50 Years of Hemoglobin Research: Unstirred and Cell-Free Layers, Electrostatics, Baseball Gloves, and Molten Globules.Antioxidants & redox signaling · 2020Review
- A reaction pathway to compound 0 intermediates in oxy-myoglobin through interactions with hydrogen sulfide and His64.Journal of molecular graphics & modelling · 2020Article
- Current Challenges in the Development of Acellular Hemoglobin Oxygen Carriers by Protein Engineering.Shock (Augusta, Ga.) · 2019Review
Corrections and comments
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Authors and funding
3 authors at 1 institution in 1 country.
Funding
Abstract
The role of the distal histidine in regulating ligand binding to adult human hemoglobin (HbA) was re-examined systematically by preparing His(E7) to Gly, Ala, Leu, Gln, Phe, and Trp mutants of both Hb subunits. Rate constants for O(2), CO, and NO binding were measured using rapid mixing and laser photolysis experiments designed to minimize autoxidation of the unstable apolar E7 mutants. Replacing His(E7) with Gly, Ala, Leu, or Phe causes 20-500-fold increases in the rates of O(2) dissociation from either Hb subunit, demonstrating unambiguously that the native His(E7) imidazole side chain forms a strong hydrogen bond with bound O(2) in both the alpha and beta chains (DeltaG(His(E7)H-bond) approximately -8 kJ/mol). As the size of the E7 amino acid is increased from Gly to Phe, decreases in k(O2)', k(NO)', and calculated bimolecular rates of CO entry (k(entry)') are observed. Replacing His(E7) with Trp causes further decreases in k(O2)', k(NO)', and k(entry)' to 1-2 microM(-1) s(-1) in beta subunits, whereas ligand rebinding to alphaTrp(E7) subunits after photolysis is markedly biphasic, with fast k(O2)', k(CO)', and k(NO)' values approximately 150 microM(-1) s(-1) and slow rate constants approximately 0.1 to 1 microM(-1) s(-1). Rapid bimolecular rebinding to an open alpha subunit conformation occurs immediately after photolysis of the alphaTrp(E7) mutant at high ligand concentrations. However, at equilibrium the closed alphaTrp(E7) side chain inhibits the rate of ligand binding >200-fold. These data suggest strongly that the E7 side chain functions as a gate for ligand entry in both HbA subunits.
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