Tadao Nakaya

Expression of a Model Peptide of a Marine Mussel Adhesive Protein in Escherichia coli and Characterization of Its Structural and Functional Properties

An expression system for a chemically synthesized gene, encoding a model peptide of marine mussel adhesive protein, was constructed in Escherichia coli under regulation of the T7-promoter. The model peptide consisted of six repeats of the decapeptide AKPSYPPTYK. Although the product was expressed as an inclusion body, we were able to solubilize it successfully, using acetic acid. The higher-order structure of this model peptide was investigated using CD spectroscopy and NMR spectroscopy. Using the modified enzyme, mushroom tyrosinase, the tyrosine residue was hydroxy- lated to 3,4-dihydoxyphenylalanine (Dopa), and the resulting modified peptide was polymerized, solidified, and insolubilized spontaneously.

Anticoagulant surface prepared by the heparinization of ionic polyurethane film

We present a new method for heparinization on the surface of polyurethane. The segmented polyurethane was first modified with an epoxide monomer and followed by a ring-opening reaction with diethanolamine to introduce sufficient hydroxyl groups on the surface of cast film. On this film surface, a cationic monomer was grafted by using tetravalent Cerium salt as an initiator. Heparin was immobilized in high efficiency on the ionized surface through static interactions in aqueous solution. The structure of ionized and heparinized surfaces were characterized by attenuated total reflectance infrared spectroscopy (ATR–FTIR) and electron spectroscopy for chemical analysis (ESCA) spectra. The platelet-rich plasma (PRP) contacting test and the platelet-poor plasma (PPP) clotting time measurements showed that the immobilized heparin retained its strong anticoagulant property. The release of heparin from film into salt solution was also studied, and it was found that only a small portion of heparin (10–20%) was released over a period as long as 10 h. It is expected that this new method for surface heparinization can be used to prepare antithrombogenic materials with long-term stability.

Synthesis and luminescent properties of europium complexes

Abstract Europium (Eu) complexes with β -diketone ligands have been synthesized and characterized using luminescence spectroscopy. Complexes with fluorene show high fluorescence in THF solution and exhibit sharp emission peak at 615 nm. We have improved the energy transfer from the blue-emitting material (host) to the Eu complex (guest) by the synthesis of a new Eu complex which exhibits an absorption peak at lower energy with respect to the emission energy of the host. With respect to volatility, since some thin films of the complexes were not formed easily by vapour deposition, we have examined the thermal properties of the Eu complexes with phenanthroline derivatives. We discuss the efficiency of the energy transfer and volatility of these complexes.

How do the x-ray structure and the NMR structure of FMN-binding protein differ?

The crystal structure of FMN-binding protein (FMN-bp) from Desulfovibrio vulgaris Miyazaki F was solved by the multiple isomorphous replacement method and refined to an R factor of 15.1% at 1.3 A resolution. FMN-bp exists in a dimeric form in the crystal, in contrast to the monomeric structure determined by NMR. R.m.s. deviations between the crystal structure and the solution structure are more than 2 A, which implies significant differences. There are some hydrophobic residues in the interface between the two monomers. In particular, Leu122 in the C-terminus has a close contact with the o-xylene moiety of FMN, while solvent molecules may cover the o-xylene moiety in the solution structure.

A Gene Encoding a Cytochrome c Oxidase‐Like Protein Is Located Closely to the Cytochrome c‐553 Gene in the Anaerobic Bacterium, Desulfovibrio vulgaris (Miyazaki F)

The gene encoding cytochrome c‐553 from Desulfovibrio vulgaris (Miyazaki F) was cloned using a synthetic oligodeoxyribonucleotide probe. The nucleotide sequence indicated that cytochrome c‐553 was synthesized as a precursor protein with an NH2‐terminal signal sequence of 23 residues. In the cloned DNA fragment, there are three other open reading frames whose products have 191, 157, 541 amino acid residues, respectively. The putative ORF‐4 product is highly homologous with the cytochrome c oxidase subunit I from various organisms.

A novel red organic electroluminescent device using Eu complex as an emitting layer

Abstract A novel europium complex, Eu(MDFP) 3 (phen) (MDFP = 5-methyl-1,3-di-(2-furyl)-1,3-propanedione, phen = 1,10-phenanthroline), was synthesized and applied to an organic electroluminescent (EL) device as an emitting material and an electron-transporting material. The double-layered EL device has been fabricated by using triphenyldiamine derivative (TPD) as a hole-transporting layer and Eu(MDFP) 3 (phen) as an active emitting layer sandwiched between indium—tin oxide (ITO) and an alloy of Al/Li (99:1) electrodes. The deposited EL device was observed to emit a bright red light originating from Eu(MDFP) 3 (phen) with a maximum luminance of 32.0 cd/m 2 at 9 V and 25.7 mA/cm 2 .

Polymerization by Carbenoids, Carbenes, and Nitrenes

Abstract Carbenes are divalent carbons, as shown by :CR2, and have two electron spin states distinguished by a singlet state (S) and a triplet state (T). One of the best methods to generate a carbene is through the decomposition of a diazo compound by irradiation or by heating, especially in the presence of a solvent or of a catalyst:

Preparation of glucose sensors using the Langmuir–Blodgett technique

Abstract A novel glucose sensor was fabricated using the Langmuir–Blodgett (LB) technique with a phospholipid analogous vinyl polymer, 2-[2-methacryloyloxy)ethyldimethyl-ammonium]ethyl-5β-cholesten-3-yl phosphate polymer (PCP). The ordered monolayers of PCP were easily prepared at the interface of air–aqueous solution containing glucose oxidase (GOD), and could be transferred onto the platinum wire electrode. The response current for the observed electrode was constant for 50 days, after an initial change of signal over the first few days.

Cloning and expression of the rubredoxin gene from Desulfovibrio vulgaris (Miyazaki F)--comparison of the primary structure of desulfoferrodoxin.

A gene encoding rubredoxin from Desulfovibrio vulgaris (Miyazaki F) was cloned and overexpressed in Escherichia coli. A 1.1-kilobase pair DNA fragment, isolated from D. vulgaris (Miyazaki F) by double digestion with SmaI and SalI, contained two genes, the rubredoxin gene (rub) and the desulfoferrodoxin gene (rbo) which was situated upstream of rub. The deduced amino acid sequence of desulfoferrodoxin was homologous to those from other strains and Cys residues that are responsible to bind irons were also conserved. The expression system for rub was constructed under the control of the T7 promoter in E. coli. The purified protein was soluble and had a characteristic visible absorption spectrum. Inductively coupled plasma-atomic emission analysis and electron paramagnetic resonance analysis of the recombinant rubredoxin revealed the presence of an iron ion in a distorted tetrahedral geometry that was the same as native D. vulgaris rubredoxin. In vitro NADH reduction analysis indicated that recombinant rubredoxin was active, and its redox potential was determined as -5 mV.

Electroluminescent devices based on polymers forming hole-transporting layers. II. Polyimides containing β-naphthyldiphenylamine units

Two polyimides, PI(C1-BA) and PI(C1-6FDA), based on an aromatic di- amine compound and two aromatic dianhydrides (biphenyltetracarboxylic dianhydride (BA) and 4,49-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)) were newly syn- thesized. They were characterized by viscosity, Fourier transform infrared measure- ments, and X-ray analyses. X-ray results revealed that the crystallinity of PI(C1-BA) was lower than that of PI(C1-6FDA). The synthesized polyimides could be formed into stable and homogeneous thin films on an ITO (indium tin oxide) electrode, functioning as good hole-transport materials for organic electroluminescent (EL) devices. The double-layered EL devices, consisting of the hole-transport layer of these polyimides and an emitting layer of tris(8-quinolinolato)aluminum complex, exhibited a peak emission wavelength in the bright green at 524 -527 nm. Moreover, a maximum luminance of 355 cd/m 2 was achieved at a voltage of 13 V, with a current density of 600 mA/cm 2 for the EL device using PI(C1-BA) as a hole-transport layer. The phenomenon of an extended luminance of these EL devices was also found when the voltage was