title: The role of an amino acid triad at the entrance of the heme pocket in human serum albumin for O(2) and CO binding to iron protoporphyrin IX.
abstract: Complexation of iron(II) protoporphyrin IX (Fe(2+)PP) into a genetically engineered heme pocket on recombinant human serum albumin (rHSA) creates an artificial hemoprotein which can bind O(2) reversibly at room temperature. Here we highlight a crucial role of a basic amino acid triad the entrance of the heme pocket in rHSA (Arg-114, His-146, Lys-190) for O(2) and CO binding to the prosthetic Fe(2+)PP group. Replacing His-146 and/or Lys-190 with Arg resolved the structured heterogeneity of the possible two complexing modes of the porphyrin and afforded a single O(2) and CO binding affinity. Resonance Raman spectra show only one geometry of the axial His coordination to the central ferrous ion of the Fe(2+)PP.
authors.affiliation: Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan. teruyuki@waseda.jp
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Komatsu
authors.forename: Akito
authors.initials: A
authors.lastname: Nakagawa
authors.forename: Stephen
authors.initials: S
authors.lastname: Curry
authors.forename: Eishun
authors.initials: E
authors.lastname: Tsuchida
authors.forename: Kenichi
authors.initials: K
authors.lastname: Murata
authors.forename: Nobuhumi
authors.initials: N
authors.lastname: Nakamura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohno
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D002248:Carbon Monoxide / Q000378:metabolism*; D003903:Deuterium / Q000737:chemistry; D004912:Erythrocytes / Q000378:metabolism; D006418:Heme / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D010100:Oxygen / Q000378:metabolism*; D011487:Protein Conformation; D011524:Protoporphyrins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012709:Serum Albumin / Q000737:chemistry* / Q000378:metabolism*; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D000596:Amino Acids; D011524:Protoporphyrins; D011994:Recombinant Proteins; D012709:Serum Albumin; C448299:iron protoporphyrin IX; D006418:Heme; D002248:Carbon Monoxide; D003903:Deuterium; D010100:Oxygen