Gerbils of a seizure-sensitive strain have a mitochondrial inner membrane protein with different isoelectric points from those of a seizure-resistant strain

The distribution of proteins in the cerebral cortex of a seizure-sensitive (SS) strain of gerbil and its seizure-resistant (SR) counterpart was profiled using two-dimensional gel electrophoresis. A series of proteins of similar molecular weight (around 83 kDa) showed small but consistent differences in their isoelectric point (pI) with indistinguishable profiles of distribution between the two strains. Amino acid sequences of peptides produced by limited proteolysis of each protein in the spots from the strains were identical or highly homologous to those of mitofilin, a mitochondrial inner membrane protein (IMMT) in humans. Analysis of cDNA sequences revealed the proteins of these spots to be gerbil mitofilin-like proteins (gIMMT), with a few base substitutions between SS and SR strains, in particular within a region near a putative transmembrane domain that is highly conserved in humans and gerbils. The amino acid at the site was acidic, Glu in humans and Asp in the strain SR of gerbil and a neutral, Asn in strain SS. In addition to these base substitutions, production of multiple species of mRNA for gIMMT by alternative splicing was observed.     

Chemical transformations of 4:7,10:13-diepoxy[15]annulenone by carbonyl transposition reactions

The titled annulenone 1 could be converted into new annulenones 3 and 8 by carbonyl transposition reactions. Compound 8 can be regarded as the first 14π hydroxy-enone as a higher homolog of tropolone (6π) and hydroxy[11]annulenones (10π), and was proved to be aromatic.     

Characterization of mouse switch variant antibodies by matrix-assisted laser desorption ionization mass spectrometry and electrospray ionization mass spectrometry

The amino acid sequences of mouse monoclonal antibodies have been characterized completely by mass spectrometry. Antibodies used in the present study were derived from mouse switch variant cell lines that produce four kinds of immunoglobulin Gs (IgGs). The amino acid sequences of these antibodies had not been estimated from the corresponding DNA sequence, so the sequences of IgGs derived from other strains were used as references in this study. Intra- and interchain disulfide bonds of the IgGs were reduced and carboxymethylated and the products were subjected to proteolytic digestion. The existence of N-linked oligosaccharides also was taken into account. The capabilities and limitations of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry and capillary liquid chromatography-electrospray ionization mass spectrometry are discussed in the structural characterization of the antibodies. Based on our results, allotypes of the antibodies examined are discussed. This study shows that amino acid sequences of proteins, such as IgG, can be investigated without information about the corresponding DNA sequence if appropriate reference sequences derived from other strains can be used.     

Kinetics of shrinking of polymer gels induced by ultracentrifugal fields

The kinetics of the shrinking of polymer gels induced by ultracentrifugal fields is investigated. A theory is proposed to describe the diffusion process of polymer networks under centrifugal fields. The initial shrinking rate is proportional to the ratio of the centrifugal force to the frictional force of networks. The shrinking attains the stationary state as a result of the balance between the centrifugal force and the swelling force of networks. The characteristic time for shrinking is of the order of a2/D where a and D are the stationary displacement and diffusion constant, respectively. We also present the experimental data for the shrinking of the poly(acrylamide) (PAAm) gels under ultracentrifugal fields. The shrinkage increases linearly with time in the initial stage whereas it reaches the steady state in the long time limit as expected by the theory. Each of longitudinal elastic modulus and friction coefficient of the PAAm gels is evaluated from the data on the basis of the theory.     

Total energies of molecules with the local density functional approximation and gaussian basis sets

Total energies of small molecules were calculated with a local density functional (LDF) approximation within the LCAO MO SCF scheme. The local spin density functional (LSD) of Gunnarsson and Lundqvist was used. The basis sets used are of contracted gaussian type which allow comparison of LSD with Hartree-Fock (HF) results. The program for calculation of the LSD term was incorporated into the standard ab initio package. The LSD binding energies were in better agreement with experiment than those from HF.     

Total synthesis of miraziridine A and identification of its major reaction site for cathepsin B

The synthesis of miraziridine A, a pentapeptide derivative isolated from marine sponge, and its truncated analogs has been achieved. To construct the backbone of miraziridine A, a side-chain-unprotected vinylogous arginine was condensed with an aziridine-containing fragment prepared by a conventional solid-phase procedure. An analog lacking the vinylogous arginine site showed comparable inhibitory activity with miraziridine A, whereas an analog lacking the aziridine site showed remarkably weak inhibitory activity for cathepsin B.     

Splitting tendency of cellulosic fibers – Part 1. The effect of shear force on mechanical stability of swollen lyocell fibers

A procedure for splitting of a lyocell fiber into a multitude of finer fibrils was developed. Crockmeter, usually used for rub-fastness of colored textiles, was modified and used for obtaining required shear force on swollen lyocell fiber. The shear force applied on fibers, and the concentration of NaOH, which affects swelling degree of fiber, were shown to be the leading parameters determining split number of lyocell fiber. While number of shear cycles was found to be of minor relevance for fiber splitting, the applied pressure directly influences the number of splitted fibrils. For example, at a pressure of 34.8 kPa, the average split number of lyocell fiber in 2.5 M NaOH solution was observed as 15, whereas it was observed as 30 for 47 kPa and 41 for 59.3 kPa. Splitting was not observed above 5 M of NaOH solution. Analyses of fiber splitting permit new aspects to study inner structure of lyocell.     

Iridium complex-catalyzed reaction of 1,6-enynes: cycloaddition and cycloisomerization

[reaction: see text] 1,6-Enynes reacted with monoynes to give cyclohexadiene derivatives in the presence of a catalytic amount of [Ir(cod)Cl](2)/ligand. DPPE was most suitable for cycloaddition. Diastereoselective cycloaddition was also possible. In the absence of monoynes, 1,6-enynes cycloisomerized to (Z)-1-alkylidene-2-methylenecyclopentane derivatives. DPPF was most suitable for cycloisomerization. These results are the first examples of highly Z-selective cycloisomerization.     

Total synthesis of an antitumor antibiotic,Fostriecin (CI-920)

The total synthesis of an antitumor antibiotic, fostriecin (CI-920), via a highly convergent route is described. A characteristic feature of the present total synthesis is that the synthesis was achieved via a coupling procedure of three segments A, B, and C. The unsaturated lactone moiety of fostriecin, corresponding to segment A, was constructed from a known Horner-Emmons reagent, and the stereochemistry of the C-5 position was introduced by asymmetric reduction with (R)-BINAl-H. Segment B having a series of stereogenic centers was synthesized from (R)-malic acid and the stereogenic centers at the C-8 and C-9 positions were prepared by a combination of Wittig reaction and Sharpless asymmetric dihydroxylation reaction. The conjugated Z,Z,E-triene moiety of fostriecin, corresponding to segment C, was eventually constructed by Wittig reaction and Stille coupling reaction. The phosphate moiety, which is known to be essentially important for the antitumor activity, was introduced via two routes: (i) direct phosphorylation of the monohydroxyl derivative in which other hydroxyl groups are protected with silyl groups; (ii) cyclic phosphorylation and selective cleavage of the cyclic phosphate derivative. Although the former route is basically the same as those reported by other groups, the latter route is novel and more effective than the former one. The present total synthesis would serve as a versatile synthetic route to not only fostriecin, but also its various analogues including stereoisomers.     

A novel,cell-permeable,fluorescent probe for ratiometric imaging of zinc ion

Zn(2+) plays important roles in various biological systems; as a result, the development of tools that can visualize chelatable Zn(2+) has attracted much attention recently. We report here newly synthesized fluorescent sensors for Zn(2+), ZnAF-Rs, whose excitation maximum is shifted by Zn(2+) under physiological conditions. Thus, these sensors enable ratiometric imaging, which is a technique to reduce artifacts by minimizing the influence of extraneous factors on the fluorescence of a probe. Ratiometric measurement can provide precise data, and some probes allow quantitative detection. ZnAF-Rs are the first ratiometric fluorescent sensors for Zn(2+) that enable quantitative analysis under physiological conditions. ZnAF-Rs also possess suitable K(d) for applications, and high selectivity against other biologically relevant cations, especially Ca(2+). Using these probes, changes of intracellular Zn(2+) concentration in cultured cells were monitored successfully. We believe that these probes will be extremely useful in studies on the biological functions of Zn(2+).