title: Characteristic of aromatic amino acid substitution at alpha 96 of hemoglobin.
abstract: Replacement of valine by tryptophan or tyrosine at position alpha96 of the alpha chain (alpha96Val), located in the alpha(1)beta(2) subunit interface of hemoglobin leads to low oxygen affinity hemoglobin, and has been suggested to be due to the extra stability introduced by an aromatic amino acid at the alpha96 position. The characteristic of aromatic amino acid substitution at the alpha96 of hemoglobin has been further investigated by producing double mutant r Hb (alpha42Tyr --> Phe, alpha96Val --> Trp). r Hb (alpha42Tyr --> Phe) is known to exhibit almost no cooperativity in binding oxygen, and possesses high oxygen affinity due to the disruption of the hydrogen bond between alpha42Tyr and beta99Asp in thealpha(1)beta(2) subunit interface of deoxy Hb A. The second mutation, alpha96Val -->Trp, may compensate the functional defects of r Hb (alpha42Tyr --> Phe), if the stability due to the introduction of trypophan at the alpha 96 position is strong enough to overcome the defect of r Hb (alpha42Tyr --> Phe). Double mutant r Hb (alpha42Tyr --> Phe, alpha96Val --> Trp) exhibited almost no cooperativity in binding oxygen and possessed high oxygen affinity, similarly to that of r Hb (alpha42Tyr --> Phe). (1)H NMR spectroscopic data of r Hb (alpha42Tyr --> Phe, alpha96Val --> Trp) also showed a very unstable deoxy-quaternary structure. The present investigation has demonstrated that the presence of the crucible hydrogen bond between alpha 42Tyr and beta 99Asp is essential for the novel oxygen binding properties of deoxy Hb (alpha96Val --> Trp) .
authors.affiliation: Department of Biochemistry Wonju 220-701, Korea.
authors.forename: Jong-Whan
authors.initials: JW
authors.lastname: Choi
authors.forename: Jong Hyuk
authors.initials: JH
authors.lastname: Lee
authors.forename: Kwang Ho
authors.initials: KH
authors.lastname: Lee
authors.forename: Hyean-Woo
authors.initials: HW
authors.lastname: Lee
authors.forename: Joon Hyung
authors.initials: JH
authors.lastname: Sohn
authors.forename: Joon Ho
authors.initials: JH
authors.lastname: Yoon
authors.forename: Byung-Il
authors.initials: BI
authors.lastname: Yeh
authors.forename: Seung Kyu
authors.initials: SK
authors.lastname: Park
authors.forename: Kyu Jae
authors.initials: KJ
authors.lastname: Lee
authors.forename: Hyun-Won
authors.initials: HW
authors.lastname: Kim
mesh_terms: D019943:Amino Acid Substitution; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D009154:Mutation / Q000235:genetics*; D010100:Oxygen / Q000378:metabolism*; D010649:Phenylalanine / Q000737:chemistry; D021122:Protein Subunits; D011994:Recombinant Proteins / Q000378:metabolism; D014364:Tryptophan / Q000737:chemistry*; D014443:Tyrosine / Q000737:chemistry*; D014633:Valine / Q000737:chemistry
chemical_list: D006454:Hemoglobins; D021122:Protein Subunits; D011994:Recombinant Proteins; D014443:Tyrosine; D010649:Phenylalanine; D014364:Tryptophan; D014633:Valine; D010100:Oxygen