title: Hemoglobin-albumin cluster incorporating a Pt nanoparticle: artificial O2 carrier with antioxidant activities.
abstract: A covalent core-shell structured protein cluster composed of hemoglobin (Hb) at the center and human serum albumins (HSA) at the periphery, Hb-HSAm, is an artificial O2 carrier that can function as a red blood cell substitute. Here we described the preparation of a novel Hb-HSA3 cluster with antioxidant activities and its O2 complex stable in aqueous H2O2 solution. We used an approach of incorporating a Pt nanoparticle (PtNP) into the exterior HSA unit of the cluster. A citrate reduced PtNP (1.8 nm diameter) was bound tightly within the cleft of free HSA with a binding constant (K) of 1.1×10(7) M(-1), generating a stable HSA-PtNP complex. This platinated protein showed high catalytic activities for dismutations of superoxide radical anions (O2•-) and hydrogen peroxide (H2O2), i.e., superoxide dismutase and catalase activities. Also, Hb-HSA3 captured PtNP into the external albumin unit (K = 1.1×10(7) M(-1)), yielding an Hb-HSA3(PtNP) cluster. The association of PtNP caused no alteration of the protein surface net charge and O2 binding affinity. The peripheral HSA-PtNP shell prevents oxidation of the core Hb, which enables the formation of an extremely stable O2 complex, even in H2O2 solution.
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University Tokyo, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Hosaka
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University Tokyo, Japan.
authors.forename: Risa
authors.initials: R
authors.lastname: Haruki
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University Tokyo, Japan.
authors.forename: Kana
authors.initials: K
authors.lastname: Yamada
authors.affiliation: Research Center of Electron Microscopy, Institute of Chemistry and Biochemistry Freie Universität Berlin, Berlin, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Böttcher
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University Tokyo, Japan.
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Komatsu
mesh_terms: D000418:Albumins / Q000737:chemistry / Q000378:metabolism*; D000975:Antioxidants; D001665:Binding Sites; D001802:Blood Substitutes; D006454:Hemoglobins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D053758:Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D010100:Oxygen / Q000378:metabolism*; D011485:Protein Binding; D013481:Superoxides / Q000037:antagonists & inhibitors
chemical_list: D000418:Albumins; D000975:Antioxidants; D001802:Blood Substitutes; D006454:Hemoglobins; D013481:Superoxides; D006861:Hydrogen Peroxide; D010100:Oxygen