Manabu Fujiwara

Preparation and characterization of novel cyclic tetranuclear manganese (III) complexes: MnIII4(X-salmphen)6 (X-salmphenH2 = N,N′-di-substituted-salicylidene-1,3-diaminobenzene (X = H, 5-Br)

Abstract Novel cyclic tetranuclear manganese(III) complexes with Schiff base ligands, N , N ′-substituted-salicylidene-1,3-diaminobenzene (X = H, 5-Br), X-salmphenH 2 , Mn III 4 (X-salmphen) 6 have been prepared and characterized by spectroscopies, magnetic susceptibility, electrochemical measurements and X-ray crystallography. Two manganese ions of the tetranuclear complexes are bridged by two X-salmphen ligands and consist of a dimer unit, [Mn 2 (X-salmphen) 2 ] 2+ . The residual two X-salmphen ligands bridge these dimer units. The resulting tetranuclear complexes constitute a dimer of the two dimetric structures that contains a intramolecular and intermolecular π-π stacking, between phenylene rings of X-salmphen ligands. The physicochemical properties of the tetranuclear complexes having a N 3 O 3 donor set are found to be analogous to those observed for tris( N -dodecyl-salicylidenaminato)manganese(III) complexes, Mn III ( N -Dod-sal) 3 . The structure of this complex is also determined by X-ray crystallography. The magnetic properties of the tetranuclear complexes indicate that there is little or no interaction among these central manganese ions.

Synthesis and self-assembly of amphiphilic zinc chlorins possessing a 31-hydroxy group

Abstract Amphiphilic zinc chlorins possessing a 3 1 -hydroxy group were prepared. Non-ionic (oligo)oxyethylene group, anionic sulfonate and cationic quaternary ammonium groups were introduced on the 17-position of a zinc chlorin moiety. All the three kinds of amphiphilic chlorophyll derivatives self-assembled in an aqueous medium to favor a formation of the anti-parallel dimeric structure. In contrast, the amphiphilic zinc chlorins formed large aggregates in non-polar organic solvent. These studies showed self-assemblies of amphiphilic zinc chlorin chromophores were controlled in environments.

Preparation and characterization of different two types of di-μ-oxo dimanganese(IV) complexes with tetradentate Schiff bases

Abstract Novel di-μ-oxo dimanganese(IV) complexes with a series of tetradentate Schiff base ligands have been prepared and characterized by spectroscopy, magnetic susceptibility, electrochemical measurements and X-ray crystallography. The di-μ-oxo dimanganese(IV) complexes, [MnIV(μ-salophen)(μ-O)], 1 (salophen H2 = N,N′-disalicylidene-1,2-diaminobenzen), [Mn(μ-salen)(μ-O)]2, 2 (salenH2 = N,N′-disalicylidene-1,2-diaminoethane), [Mn(salen)(μ-O)]2, 3, [Mn(salipn)(μ-O)]2, 4 (salipnH2 = N,N′-disalicylidene-1,2-diaminopropane) and [Mn(salbn)(μ-O)]2, 5 (salbnH2 = N,N′-disalicylidene-1,4-diaminobutane), have been found to be obtained by the reaction of the tetradentate Schiff base ligands and potassium permanganate (KMnO4) in MeCN with stirring at room temperature. X-ray analysis revealed that these complexes are classified by two different types of di-μ-oxo manganese(IV) complexes in the coordination features of the liglands; one of them (1 and 2) has a structure in which salophen or salen ligands are coordinated to two manganese ions as a bridging bidentate ligand, whereas the other (3,4 and 5) has a structure in which salen, salipn or salbn ligands are coordinated to each manganese ion as a tetradentate ligand. These types were characterized from their IR spectra around 650 cm−1, UV-vis spectra and electrochemical properties.

Structures of four types of novel high-valent manganese complexes obtained by the reactions of KMnO4 with tridentate schiff base ligands

Abstract X-ray structure analysis revealed that four types of novel manganese complexes, MnIV(N-EtO-sal)2, MnIII(N-PhO-sal)(L), [MnIV(5,6-Benzo-L)2(μ-O)]2 and MnIII(L-4-Me)3 have been found to be obtained by the reactions of KMnO4 with various tridentate Schiff base ligands (N-EtOH-salH, N-PhOH-salH and its derivatives) in dry MeCN, where N-EtOH-salH, N-PhOH-salH, LH, 5,6-Benzo-LH and L-4-MeH denote N-2-hydroxyethyl-salicylideneamine, N-2-hydroxyphenyl-salicylideneamine, 2-(2-hydroxyphenyl)-benzoxazole 2-(2-hydroxynaphthyl)-benzoxazole and 2-(2-hydroxyphenyl)-5-methylbenzoxazole, respectively. The reactions of KMnO4 and N-PhOH-salH and its derivatives have especially been found to afford benzoxazole derivatives which may be formed by intramolecular oxidative coupling between the phenolic oxygen atom of aminophenol moiety and the carbon atom of imine moiety.

Legumain from bovine kidney: its purification, molecular cloning, immunohistochemical localization and degradation of annexin II and vitamin D-binding protein.

Legumain (asparaginyl endopeptidase) was purified to homogeneity from bovine kidneys. The molecular mass of the purified enzyme was calculated to be 34000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence of beta-mercaptoethanol. The enzyme rapidly hydrolyzed the substrate Z-Ala-Ala-Asn-MCA and was strongly inhibited by N-ethylmaleimide, p-chloromercuribenzene-sulfonic acid, Hg(2+) and Cu(2+). The amino acid sequence of the first 26 residues of the enzyme was Gly-Gly-Lys-His-Trp-Val-Val-Ile-Val-Ala-Gly-Ser-Asn-Gly-Gln-Tyr-Asn-Tyr-Arg-His-Gln-Ala-Phe-Ala-Asp-His-. This sequence is highly homologous to the sequences in the N-terminal of pig kidney legumain. We screened a bovine kidney cortex cDNA library using a DNA probe that originated from rat legumain, and we determined the bovine kidney cDNA structure and deduced the amino acid sequence. The cDNA is composed 1934 bp and encodes 433 amino acids in the coding region. The enzyme was strongly stained in the proximal tubules of the rat kidney in an immunohistochemical study. Vitamin D-binding protein which is known to be a ligand to megalin existing in the proximal tubules, was cleaved in a limited proteolytic manner by bovine kidney legumain. These results suggested that legumain contributes to the processing of macromolecules absorbed by proximal tubule cells. The enzyme also cleaved an N-terminal synthetic peptide of bovine annexin II (Gly(24)-Ser-Val-Lys-Ala-Tyr-Thr(30)-Asn-Phe-Asp-Ala-Glu(35)-Arg-Asp(37)) at a position between Asn(31) and Phe(32). The amino-terminal domain of annexin II has p11 subunit binding sites and phosphorylation sites for both pp60(src) and protein kinase C. This suggests that legumain plays an important role in inactivation and degradation of annexin II, which is abundant in the receptor-recycling compartments of endosomes/lysosomes.

Evaluation of Mn3s X-ray photoelectron spectroscopy for characterization of manganese complexes

Abstract The Mn2p and Mn3s X-ray photoelectron spectra (XPS) of manganese(II), manganese(III) and manganese(IV) complexes with a variety of coordination structures were measured. Compared with the data for peak positions of Mn2p XPS, those of Mn3s XPS are found to be strongly influenced by the formal charge of the central manganese ion: the peak positions are shifted to higher energies with an increase in oxidation state. In addition, the shapes of Mn3s XPS may be also influenced by the coordination structures of the manganese complexes.

Chemical shift and lineshape of high-resolution Ni Kα x-ray fluorescence spectra

Nickel K-L (Kα) x-ray fluorescence spectra of 32 kinds of materials containing nickel [NiF 2 , NiSO 4 , Ni(CO 3 ) 2 , Ni(OH) 2 , Ni 2 O 3 , NiTiO 3 , NiO, NiFe 2 O 4 , NiCl 2 , NiBr 2 , NiI 2 , LiNiO 2 , NiS, NiTe, Ni 3 P, metal, LaNi 5 , Ni 2 P, NiCr, Ni 2 Si, NiB, NiSi 2 , acetylacetonate, K 2 Ni(CN) 4 , and some nickel complexes] were measured using a double-crystal x-ray fluorescence spectrometer. The shift, asymmetry and spin-orbit splitting energy were extracted from the measured spectra. The asymmetric Kα lineshape was deconvoluted by Lorentzian functions. It is demonstrated that the chemical state of nickel in an unknown material can be analyzed by the use of these parameters.

Rat tripeptidyl peptidase I: molecular cloning, functional expression, tissue localization and enzymatic characterization.

Abstract We purified tripeptidyl peptidase I (TPP I) to homogeneity from a rat kidney lysosomal fraction and determined its physicochemical properties, including its molecular weight, substrate specificity and partial amino acid sequence. The molecular weight of the enzyme was calculated to be 280 000 and 290 000 by nondenaturing PAGE and gel filtration, respectively, and to be 43 000 and 46 000 on SDSPAGE in the absence and presence of βME, respectively. These findings suggest that the enzyme is composed of six identical subunits. The Km , Vmax , kcat and kcat/Km values of TPP I at optimal pH (pH 4.0) were 680 M, 3.7 molper mg and min, 33.1 per s and 4.87 10,000 per s and M for AlaAlaPheMCA, respectively. TPP I was significantly inhibited by PCMBS and HgCl 2 , and moderately by DFP. These findings also suggest that TPP I is an exotype serine peptidase that is regulated by SH reagent. TPP I released the tripeptide ArgValTyr from angiotensin III more rapidly than from AlaAlaPheMCA, and also released GlyAsnLeu from neuromedin B with the same velocity as from AlaAlaPheMCA. Angiotensin III and neuromedin B have recently been found to be good natural substrates for lysosomal TPP I. Furthermore, we determined the rat liver cDNA structure and deduced the amino acid sequence. The cDNA, designated as λRTI-1, is composed of 2485 bp and encodes 563 amino acids in the coding region. By Northern blot analysis, the order for TPP I mRNA expression was kidney > / = liver > heart > brain > lung > spleen >> skeletal muscle and testis. In parallel experiments, the TPP I antigen was detected in various rat tissues by immunohistochemical staining.

Preparation and structures of trinuclear manganese(II) complexes with N-2-pyridiylmethylidene-2-hydroxy-5-substituted-phenylamine

Abstract The trinuclear manganese(II) complexes, [MnII3(OAc)4(pap)2(H2O)2] and [MnII3(OAc)4(5-Cl-pap)2(MeOH)2] were prepared by the reaction of tridentate Schiff base ligands X-papH (X=H, Cl), [N-2-pyridiylmethylidene-2-hydroxy-5-substituted-phenylamine], and MnII(OAc)2·2H2O. In the molecular structures of these complexes, two terminal manganese ions are coordinated with one oxygen and two nitrogen atoms of X-pap, two oxygen atoms of OAc− and a solvent molecule, to form a distorted octahedral structure where the central manganese ion resides on a center of symmetry and is surrounded by an O6 donor set of four oxygen atoms from four bridging OAc− and two phenolic oxygen atoms of two X-pap ligands.

Novel dinuclear manganese(III) complexes with bi- or tridentate and bridging tetradentate Schiff base ligands: preparation, properties and catalase-like function

Abstract Novel mono- and dinuclear manganese(III) complexes: [MnIII(acac)(PA)2] (1), [MnIII(acac)(N-OPh-sal)(EtOH)] (2), [MnIII2(PA)4(sal-m-xylylene)] (3), [MnIII2(N-OPh-sal)2(X-sal-m-xylylene)] (X=H (4a), 5-MeO (4b), 3-MeO (4c), 5-Br (4d), and 5-NO2 (4e)), and [MnIII2(N-OPh-sal)2(X-salpentn)] (X=H (5a) and 5-MeO (5b)) have been prepared by ligand substitution reactions and characterized, where Hacac, HPA, N-HOPh-Hsal, H2X-sal-m-xylylene, and H2X-salpentn denote acetylacetone, picolinic acid, N-hydroxyphenyl-salicylideneamine, N,N′-di-substituted-salicylidene-m-xylylenediamine, and N,N′-di-substituted-salicylidene-1,5-pentanediamine, respectively. Single crystals of complexes 1, 2, 4a, and 5a were used for X-ray crystallographic determination. Complexes 1 and 2 have a mononuclear structure, in which the central manganese(III) ions adopt a distorted octahedral geometry having an elongated axial bond compared to the equatorial bonds due to the Jahn–Teller effect. For complexes 4a and 5a, their detailed structures could not be clarified owing to a disorder of their molecules and quick degradation of the crystals in air. However, the results suggested that the two manganese(III) ions in these complexes are bridged by one sal-m-xylylene or salpentn ligand to form a dinuclear complex, and each complex has an arrangement similar to that of the mononuclear complex 2. The reactivities of these manganese(III) complexes toward H2O2 have been found that the dinuclear complexes 4a–e, 5a, and 5b can decompose excess amounts of H2O2 (H2O2/Mn