title: Molecular assembly of zinc chlorophyll derivatives by using recombinant light-harvesting polypeptides with His-tag and immobilization on a gold electrode.
abstract: LH1-α and -β polypeptides, which make up the light-harvesting 1 (LH1) complex of purple photosynthetic bacteria, along with bacteriochlorophylls, have unique binding properties even for various porphyrin analogs. Herein, we used the porphyrin analogs, Zn-Chlorin and the Zn-Chlorin dimer, and examined their binding behaviors to the LH1-α variant, which has a His-tag at the C-terminus (MBP-rubα-YH). Zn-Chlorin and the Zn-Chlorin dimer could bind to MBP-rubα-YH and form a subunit-type assembly, similar to that from the native LH1 complex. These complexes could be immobilized onto Ni-nitrilotriacetic acid-modified Au electrodes, and the cathodic photocurrent was successfully observed by photoirradiation. Since Zn-Chlorins in this complex are too far for direct electron transfer from the electrode, a contribution of polypeptide backbone for efficient electron transfer was implied. These findings not only show interesting properties of LH1-α polypeptides but also suggest a clue to construct artificial photosynthesis systems using these peptide materials.
authors.affiliation: Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Sakai
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Noji
authors.forename: Masaharu
authors.initials: M
authors.lastname: Kondo
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Mizuno
authors.forename: Takehisa
authors.initials: T
authors.lastname: Dewa
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ochiai
authors.forename: Hisanori
authors.initials: H
authors.lastname: Yamakawa
authors.forename: Shigeru
authors.initials: S
authors.lastname: Itoh
authors.forename: Hideki
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Mamoru
authors.initials: M
authors.lastname: Nango
mesh_terms: D002734:Chlorophyll / Q000096:biosynthesis* / Q000737:chemistry*; D004566:Electrodes; D006046:Gold / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry / Q000378:metabolism*; D055767:Immobilized Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D015032:Zinc / Q000737:chemistry*
chemical_list: D055767:Immobilized Proteins; D045342:Light-Harvesting Protein Complexes; D010455:Peptides; D011994:Recombinant Proteins; D002734:Chlorophyll; D006639:Histidine; D006046:Gold; D015032:Zinc