A Feruloyl Esterase (FAE) Characterized by Relatively High Thermostability from the Edible Mushroom Russula virescens

A monomeric feruloyl esterase (FAE) with a molecular mass of 62 kDa was acquired from fresh fruiting bodies of the edible mushroom Russula virescens. The isolation procedure involved ion exchange chromatography on CM-cellulose, Q-Sepharose, and SP-Sepharose and finally fast protein liquid chromatography–gel filtration on Superdex 75. Two amino acid sequences were obtained after tryptic digestion, and they both showed some homology with the esterase of some fungi. Maximal activity was observed at pH 5.0 and at 50 °C. The enzyme displayed relatively high thermostability as evidenced by over 70 % residual activity at 70 °C and about 34 % residual activity at 80 °C. The K _m and V _max for this enzyme on methyl ferulate were 0.19 mM and 1.65 U/mg proteins, respectively. The purified FAE prefers methyl ferulate over methyl caffeate and is least active on methyl p-coumarate. The FAE activity was not significantly affected by the presence of cations such as Mn²⁺, Ca²⁺, Cd²⁺, Zn²⁺, Mg²⁺, Cu²⁺, and K⁺ ions but inhibited by Al³⁺, Hg²⁺, Fe²⁺, and Pb²⁺ ions at a tested concentration of 2. 5 mM.     

二苯并噻吩在分散型钼催化剂和原位产生的氢存在下的加氢脱硫Ⅲ. 催化剂前身物、硫化氢、一氧化碳和水对反应的影响(英)

研究了水／ 甲苯乳化液中二苯并噻吩（ 硫芴） 在分散型钼酸、磷钼酸和四硫钼酸铵催化剂存在下的加氢脱硫反应． 反应在高压釜中于３４０ ℃及三种不同的气氛即Ｈ２ ,Ｈ２／Ｈ２ Ｏ和ＣＯ／Ｈ２Ｏ（ＣＯ 和Ｈ２Ｏ 经水煤气转换反应（ ＷＧＳＲ） 产生原位氢） 的存在下进行． 用ＧＣ和ＧＣＭＳ鉴定、分析了气体和液体产物的组成． 结果表明： 对硫芴的加氢脱硫反应,在分散型四硫钼酸铵催化剂存在下,原位产生的氢的效果仅比加入的氢气稍好,而在分散型钼酸和磷钼酸催化剂存在下,原位产生的氢远比加入的氢气有效． 实验结果还表明： 硫化氢能显著提高分散型钼酸和磷钼酸催化剂的加氢脱硫活性,但在分散型四硫钼酸铵催化剂存在下,硫化氢能促进加氢反应而抑制氢解反应． 一氧化碳和水均选择性地抑制氢解反应．     

A simple reliable approximation for isotropic intermolecular forces. A critical test using HH(3Σu+) as a model

A simple semi-empirical approximation for the exchange energy (E_x), coupled with a tractable representation of the Coulomb energy (E_C), has been found to yield very accurate results for the isotropic part of the interaction energy (E_int = E_x + E_C) between two closed shell systems. The expression for E_int is based on the knowledge of the first order Coulomb energy and the first three terms in the asymptotic long range expansion of the second order Coulomb energy for the interaction and contains but one adjustable parameter which occurs in E_x. The usefulness of this approach for evaluating E_int is tested critically by using the non-bonded H(1s)H(1s) (³Σ_u⁺) interaction as a model (accurate values of the total interaction energy, the exchange energy, and various orders of Coulomb energies, are available for a wide range of R for this system). The results obtained for both E_int and (dE_int/dR) are inremarkable agreement with the exact results of Kotos and Wolniewicz for R > 3 a_o. Since the law of corresponding states for inert gas pairs holds equally well for the HH(³Σ_u⁺) interaction, our analysis of this simple system yields valuable information on the reliability of the approach for other van der Waals dimers.     

Determination of bepridil in biological fluids by high-performance liquid chromatography

A rapid, selective and sensitive assay has been developed for the determination of the anti-anginal drug, bepridil, in biological samples. The lowest concentration of bepridil which can be measured accurately and precisely in a 2-ml plasma or urine sample is 10 ng/ml. The standard curve is linear in the concentration range 10-2000 ng/ml. Accuracy and precision of the assay, expressed as relative deviation and coefficient of variation (inter-run) are less than 6.5% at all concentrations in the linear range. No interfering peaks are observed. Using an automatic injector and a laboratory computer system, 48 samples are analyzed routinely in an 8-h day.     

Ternary and binary copper(II) complexes: synthesis,characterization, ROS-inductive,proteasome inhibitory,and anticancer properties

Three ternary copper(II) complexes, [Cu(phen)(L-phe)Cl]·2H₂O, [Cu(phen)(L-leu)Cl]·4½H₂O, and [Cu(phen)(L-tyr)Cl]·3H₂O, and four binary copper(II) complexes, [Cu(phen)Cl₂]_, Cu(L-phe)₂·½H₂O, Cu(L-leu)₂·½H₂O, and Cu(L-tyr)₂·H₂O (where phen = 110-phenanthroline, L-phe = L-phenylalanine, L-tyr = L-tyrosine, L-leu = L-leucine and Cl^- = chloride), were synthesized and characterized by elemental analysis, spectroscopic techniques (FTIR, UV–visible, fluorescence spectroscopy), magnetic susceptibility, molar conductivity, and lipophilicity measurement. X-ray diffraction determination of a single crystal of [Cu(phen)(L-tyr)Cl] showed two independent molecules in the asymmetric unit, each with the same distorted square pyramidal geometry about copper(II). p-Nitrosodimethylaniline assay revealed that the three ternary complexes were better inducers of reactive oxygen species over time than binary complexes, CuCl₂, and free ligands. All the copper(II) complexes in this series inhibited the three proteolytic activities in the order Trypsin-like > Caspase-like > Chymotrypsin-like. In terms of anticancer properties, the copper(II)-phen complexes had GI50 values of less than 4 μM against MCF-7, HepG2, CNE1 and A549 cancer cell lines, more potent than cisplatin.     

Organostannate derivatives of dicyclohexylammonium hydrogen 2,6-pyridinedicarboxylate: solution/solid-state 13C,119Sn NMR and in vitro antitumour activity of bis(dicyclohexylammonium) bis(2,6-pyridinedicarboxylato)dibutylstannate,and the crystal structure of its monohydrate

Bis(dicyclohexylammonium) bis(2,6-pyridinedicarboxylato)dibutylstannate is assigned seven-fold coordination at tin on the basis of its ¹¹⁹Sn CP/MAS NMR chemical shift (δ=−424.9 ppm). The assignment has been corroborated by a crystal structure determination of its monohydrate, whose tin atom has the trans -C₂SnNO₄ pentagonal bipyramidal [Sn–C=2.040(9), 2.067(8) Å; C–Sn–C =168.9(5)°] geometry. One 2,6-pyridine- dicarboxylato group chelates to the tin atom (Sn–O=2.234(4), 2.260(4); Sn–N =2.279(5) Å) whereas the other binds through only one carboxyl –CO₂ end (Sn–O=2.416(5), 2.441(5) Å). Hydrogen bonds link the cation and the stannate into a linear chain parallel to the b -axis. The lattice water molecule is hydrogen-bonded to the free carboxyl end. The anhydrous compound showed higher in vitro antitumor activity than those of carboplatin and cisplatin when screened against breast (MCF-7, EVSAT), colonic (WiDr), ovarian (IGROV) and renal (A498) carcinoma, and melanoma (M19 MEL) cell lines. © 1997 by John Wiley & Sons, Ltd.