title: Non-covalent modification of the heme-pocket of apomyoglobin by a 1,10-phenanthroline derivative.
abstract: To expand the repertoire of artificial enzymes that are constructed by replacing the natural prosthetic group of hemoproteins with non-natural cofactors, we examined incorporation of a non-porphyrinic ligand (1) into the heme-pocket of apomyoglobin in a non-covalent fashion. Ligand 1 is a highly conjugated 1,10-phenanthroline derivative, which shares some structural features with protoporphyrin IX; for example, molecular size and arrangement of hydrophobic and anionic parts. Addition of apomyoglobin to a solution of 1 induces clear changes in the absorption spectrum of 1, suggesting one-to-one incorporation of 1 into the heme cavity of apomyoglobin with an affinity of 6.3 x 10(6)M(-1). We found that the hydrolytic activity of apomyoglobin toward p-nitrophenyl hexanoate was greatly suppressed because of the incorporation of 1 into the heme-pocket.
authors.affiliation: Department of Molecular Engineering, Kyoto University, Kyoto Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan. hitomi@moleng.kyoto-u.ac.jp
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hitomi
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Mukai
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yoshimura
authors.forename: Tsunehiro
authors.initials: T
authors.lastname: Tanaka
authors.forename: Takuzo
authors.initials: T
authors.lastname: Funabiki
mesh_terms: D000818:Animals; D001059:Apoproteins / Q000737:chemistry* / Q000187:drug effects; D001665:Binding Sites; D006418:Heme / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009211:Myoglobin / Q000737:chemistry* / Q000187:drug effects; D010618:Phenanthrolines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D011524:Protoporphyrins / Q000737:chemistry; D013045:Species Specificity; D050661:Sperm Whale; D013329:Structure-Activity Relationship
chemical_list: C508193:2,9-bis(3,5-dicarboxylphenylethynyl)phenanthroline; D001059:Apoproteins; D008024:Ligands; D009211:Myoglobin; D010618:Phenanthrolines; D011524:Protoporphyrins; C010857:apomyoglobin; D006418:Heme; C028025:protoporphyrin IX; C025205:1,10-phenanthroline