Paper electrophoretic properties of surfactants in aqueous systems

Summary The electrophoretic mobilities for the micelles of sodium dodecyl sulfate and sodium dodecyltrioxyethylene sulfate in the presence of various electrolytes were measured by paper electrophoresis and compared with the mobilities obtained from Tiselius- type electrophoresis. There is a good correlation between the mobility from paper electrophoresis (U _P ) and that from Tiselius electrophores is (U _T ), and a factor in conversion from U _P to U _T was found to be 0.60. The value is not affected by the type of electrolytes present and the ionic strength of solutions. In addition, the paper electrophoretic behavior of the micelles of sodium dodecyl sulfate in the aqueous solutions of a series of sodium polyphosphates was also investigated.

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Zusammenfassung In der vorliegenden Arbeit wird die Bestimmung der elektrophoretischen Beweglichkeit von Mizellen durch Papier-Elektrophorese mit der Bestimmung in einer Tiselius-Apparatur verglichen. Die mit Hilfe der Papier-Electrophorese ermittelten Beweglichkeiten sind um einen konstanten Faktor kleiner als die Werte in der Tiselius-Apparatur. Der Faktor 0.60 ist unabh?ngig von dem Elektrolyt-Typ und der Ionenst?rke in der L?sung. Die Beweglichkeiten k?nnen über Papier-Elektrophorese auch dann gemessen werden, wenn Bestimmungen in der Tiselius-Apparatur nicht m?glich sind, z. B. bei Natriumdodecylsulfat in L?sungen von Natriumpolyphosphaten.

     

Coupling length due to random bending in multimode optical fibres

Mode coupling coefficients and coupling lengths are determined for multimode fibres with general index distributions in the case where random bending is the main cause of mode coupling. It is shown that the product of the coupling length and the coupling-induced loss is determined only by the shape of the index distribution, and that the coupling length of the focusing fibre is about four times longer than that of the step-index fibre when the coupling-induced losses of both fibres are equal.     

Anion-controlled assembly of four manganese ions: structural, magnetic, and electrochemical properties of tetramanganese complexes stabilized by xanthene-bridged Schiff base ligands

The reaction of manganese(II) acetate with a xanthene-bridged bis[3-(salicylideneamino)-1-propanol] ligand, H(4)L, afforded the tetramanganese(II,II,III,III) complex [Mn(4)(L)(2)(μ-OAc)(2)], which has an incomplete double-cubane structure. The corresponding reaction using manganese(II) chloride in the presence of a base gave the tetramanganese(III,III,III,III) complex [Mn(4)(L)(2)Cl(3)(μ(4)-Cl)(OH(2))], in which four Mn ions are bridged by a Cl(-) ion. A pair of L ligands has a propensity to incorporate four Mn ions, the arrangement and oxidation states of which are dependent on the coexistent anions.     

INTRACELLULAR TARGET FOR α-TERTHIENYL PHOTOSENSITIZATION: INVOLVEMENT OF LYSOSOMAL MEMBRANE DAMAGE

Abstract— Intracellular targets for the photosensitizer α-terthienyl (αT) were examined by fluorescence microscopy and microfluorospectrometry using human nonkeratinized buccal cells. Intracellular distribution of αT was observed as fluorescent patches widely dispersed in the cytoplasm. The distribution of the fluorescent patches was compared with that of acid phosphatase activity visualized as an azo dye produced by the fast garnet 2-methyl-4-[(2-methyl-phenyl)azo]benzenediasonium sulfate reaction. Because both the distribution sites coincided, lysosomes were the likely sites of intracellular affinity of αT. However, because acid phosphatase is not a specific lysosomal marker, we tried to detect another lysosomal enzyme, β-galactosidase, to confirm if the fluorescent patches were lysosomes, using fluorescein-di-(β-D-galactopyranoside) (FDG) as a fluorogenic substrate. Without UV-A (320–400 nm) irradiation of the cells after uptake of αT and FDG, no significant fluorescence was observed. In contrast, with prior UV-A irradiation in the presence of αT and FDG, the bright yellow fluorescence of fluorescein, which is the digested product of FDG, was clearly detected in the cells by fluorescence microscopy. This observation implied that inflow of external FDG into the lysosomes is caused by lysosomal membrane damage on αT photosensitization. The present results indicated that lysosomes are the primary photosensitization site of αT.     

Role of Water Activity on the Synthesis of Vinyl Thymidine Catalyzed by Protease from Bacillus Subtilis

The transesterification activity of Bioprase, a protease from Bacillus subtilis, in dimethylformamide (DMF) is found to depend strongly on water addition. For the transesterification between thymidine and divinyl adipate by Bioprase in DMF with water (5–40%), the conversion rate of thymidine to the ester is much higher than the rate in DMF without the addition of water. For example, the transesterification reaction of 0.25 M thymidine with 1 M divinyl adipate in DMF in the presence of 10% water was catalyzed by Bioprase (50 mg · ml^?1) at 30 °C for only 10–20 minutes to give 5′‐O‐vinyladipoyl thymidine (conversion ca. 90%), but the reaction did not proceed without the addition of water. Furthermore, the water effect is useful for the transesterification of thymidine with divinyl sebacate, which has a longer alkyl chain than divinyl adipate. This investigation showed that DMF adsorbs on the enzyme surface instead of essential water in the reaction of DMF without addition of water. On the other hand, in the reaction of DMF/water cosolvents, essential water bound to enzyme was not removed by DMF, and a higher transesterification activity occurs thereafter.

Effect of water on the transesterification of thymidine catalyzed by Bioprase in DMF.     

Application of fragment molecular orbital scheme to silicon-containing systems

The fragment molecular orbital (FMO) scheme has been successfully used for a variety of large-scale molecules such as proteins and nucleic acids so far. We have applied the FMO calculations to the silicon-containing systems like polysilanes. The error caused by the fragmentation was examined by the Hartree–Fock method and the second-order Møller-Plesset (MP2) perturbation method for the ground state energy. The dynamic polarizability as a linear response property was also evaluated with and without the fragmentation. A series of numerical comparisons showed that the FMO scheme is applicable to silicon-based molecules with reasonable accuracy. This implied a potential availability of FMO calculations for the issues relevant to nanoscience and nanotechnology.     

Fragment interaction analysis based on local MP2

We have developed a fragment interaction analysis based on local MP2 (FILM) in the context of the fragment molecular orbital (FMO) scheme. The primary purpose of this work is to provide a tool for analyzing inter-fragment interaction associated with dispersion interactions in a large molecule such as protein and DNA. Our implementation of local MP2 (LMP2) is based on the algorithm developed by Pulay and Werner. A potential of FILM was demonstrated using the human immunodeficiency virus type 1 protease (HIV-1 PR) complexed with lopinavir (LPV). The total energy, binding affinity, and inter-fragment interaction energy (IFIE) by the FMO method using LMP2 were compared with those obtained by canonical MP2 and the site-specific information in dispersion interaction was obtained. It turned out that the FILM is a useful tool for analyzing the dispersion interaction between an amino acid residue and a specific site of a ligand.     

Synthesis of metal‐free poly(1,4‐dioxan‐2‐one) by enzyme‐catalyzed ring‐opening polymerization

To avoid the harmful effects of metallic residues in poly(1,4‐dioxan‐2‐one) (PPDO) for medical applications, the enzymatic polymerization of 1,4‐dioxan‐2‐one (PDO) was carried out at 60 °C for 15 h with 5 wt % immobilized lipase CA. The lipase CA, derived from Candida antarctica, exhibited especially high catalytic activity. The highest weight‐average molecular weight (M_w = 41,000) was obtained. The PDO polymerization by the lipase CA occurred because of effective enzyme catalysis. The water component appeared to act not only as a substrate of the initiation process but also as a chain cleavage agent. A slight amount of water enhanced the polymerization, but excess water depressed the polymerization. PPDO prepared by enzyme‐catalyzed polymerization is a metal‐free polyester useful for medical applications. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1560–1567, 2000