bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation of Azulenequinone Derivatives from Variously Functionalized Azulenes by Bromine‐oxidation
Authors: Yang Paw‐Wang , Chen Jhy‐An , Wakabayashi Hidetsugu , Shindo Kimio , Kurihara Teruo , Wu Chi‐Phi , Yasunami Masafumi , Nozoe (The Late) Tetsuo 
Published: May 2015

AbstractVariously functionalized 1,5‐ and 1,7‐azulenequinones were easily derived in one‐pot in 30‐50% yield from the bromine‐oxidation of 2‐methoxyazulene and 2‐methyl derivatives of 1‐cyano‐, 1‐methoxycarbonyl‐ and its 7‐isopropyl derivatives, while 1‐methoxycarbonylazulene afforded several unstable products from which we could not isolate any azulenequinones. 1‐Acetylazulene afforded 3‐bromo‐1,5‐ and ‐1,7‐azulenequinones via side‐chain brominated intermediates in high yield. 1,3‐Dichloroazulene afforded a mixture of 3‐chloro‐1,5‐ and −1,7‐azulenequinones, while 1‐fluoro‐ and 1,3‐diiodoazulene gave a mixture of 3‐bromoazulenequinones. Analogous oxidation of 1,3‐difluoroazulene produced 3‐fluoroazulenequinones, but we could not isolate them due to its instability. Hydroxy group of 2‐(3‐hydroxypropyl)azulene was intact during this quinone formation reaction.
The Analysis of Sulfur Compounds by Solid Adsorbent Tenax GR Preconcentration and Gas Chromatography with Flameless Sulfur Chemiluminescence Detection
Authors: Sye Wen‐Fa , Cheng Mei‐Fang 
Published: May 2015

AbstractGas chromatography using flameless sulfur chemiluminescence detection was applied to the analysis of sulfur compounds in air. A trap employing the solid adsorbent Tenax GR was used to enrich ambient levels of volatile sulfur compounds. The sulfur gases were then thermally released according to programmed temperature from the adsorbent trap and re‐collected in a column cooled with liquid nitrogen. The sulfur compounds were revolatilized and directly transferred to the system of PLOT‐column gas chromatograph/flameless sulfur chemiluminescence detector for analysis. The PTV injector has been used as a thermal resorption chamber for analysis of sulfur compounds. The sulfur gaseous compounds known to cause nuisance odors in the air from sewerage treatment works were determined.
A Model Study of Intramolecular Asymmetric Radical Cyclizations of α‐Ester and α‐Amide Radicals
Authors: Yeh Ru‐Long , Jiaang Weir‐Tom , Tsai Yeun‐Min 
Published: May 2015

AbstractStarting from malonate, a practical route was developed for the synthesis of α‐phenylthio acid 3. Several chiral compounds including (‐)‐menthol, (‐)‐8‐pbenylmenthol and a camphor based oxazolidinone 8 reacted with 3 to give α‐phenylthio esters or amide. These sulfides cyclized efficiently when reacted with tributyltin hydride. Among the chiral auxiliaries used, 8‐phenylmenthyl group displayed moderate asymmetric induction (64% ee for cis‐product and 40% ee for trans‐product). Based on this results, a transition state model was proposed to explain the observed stereoselectivity. In this model, due to π,π‐orbital overlap of the phenyl ring and the carbonyl, the si‐face of the most stable conformer of the radical was shielded. This controlled the carbon‐carbon bond formation to occur from the re‐face.
Constituents of the Bark of Ficus microcarpa Lf.
Authors: Kuo Yueh‐Hsiung , Li Yen‐Cheng 
Published: May 2015

AbstractThe isolation and identification of twenty‐eight crystalline components from the bark of Ficus microcarpa L.f. are described. Their structures were determined on the basis of spectral data and values taken from the literature. These compounds include fourteen triterpenoids, one fatty alcohol, eight steroids, one coumarin, one flavane, two 4‐hydroxybenzoates, and one carotenoid‐like compound.
Chemical Constituents of Heartwood of Bauhinia purpurea
Authors: Kuo Yueh‐Hsiung , Yeh Ming‐Hsi 
Published: May 2015

AbstractThe isolation and identification of twenty‐two components from the heartwood of Bauhinia purpurea are described. Their structures were determined on the basis of spectral evidence as well as direct comparison with authentic samples. Those components included six steroids, two triterpenoids, three fatty alcohol, acid and ester, two glycerols, five flavonoids, two phenols, one chromone, and one sugar. Among these, 6′‐(β‐sitosteryl‐3‐O‐β‐glucopyranosidyl)tetraeicosanoate is a new compound.
Conductometric Flow‐Injection Glucose Biosensing System with an Immobilized Glucose‐Oxidase Mini‐Reactor
Authors: Chen Richie L. C. , Chang Bin‐Wha , Chang Hsien‐Chang 
Published: May 2015

AbstractA flow‐injection conductometric manifold equipped with an immobilized glucose‐oxidase mini‐reactor was proposed for the determination of glucose concentration. The glucose of the injected sample plug was oxidized enzymatically to its δ‐lactone, and the hydrolysis of the lactone generated a concentration‐dependent flow‐injection signal. The dynamic range was from the tens of μM to the mM order of glucose; the immobilized enzyme reactor was stable for at least several months. The pH of the carrier solution was maintained in a slightly alkaline region (ca. 8.0 by 500 μM of Tris‐HCl) to accelerate the spontaneous hydrolysis of δ‐gluconolactone. The repeatability of the flow‐injection signals was improved (CV < 3%, n = 7) by the addition of Triton X‐100® (0.7% w/v) into the carrier solution.
Efficient, Optimized Applications of p‐Nitrophenyl Active Ester Temporarily Protecting Groups Together with Simultaneous Activation in Synthesis of Special Glu and Lys Peptides
Authors: Szókán Gy. , Almás M. , Kótai A. , Khlafulla A. R. 
Published: May 2015

AbstractBenzyloxycarbonyl‐glutamylpeptide p‐nitrophenylesters were prepared from protected amino acids, e.g.: p‐nitrophenyl‐glutamate as carboxyl component and aminoacid or peptide p‐nitrophenylesters as amino components by different kinds of peptide coupling methods. Mixed carbonic anhydride and azide methods gave good results. The p‐nitrophenylesters existed as temporary protecting groups, so the peptide couplings proceeded together with simultaneous activation. The conditions and applications of the procedure are discussed. The peptides having one or more active ester groups were used to form amides by their aminolysis with derivatives of ethylamine or were polycondensated (after deprotection) to obtain polypeptides.
Dioxins in Soil and Fish Samples from a Waste Pentachlorophenol Manufacturing Plant
Authors: Soong Der‐Kau , Hou Peter C. C. , Ling Yong‐Chien 
Published: May 2015

AbstractA method to analyze polychlorinated dibenzo‐p‐dioxins and dibenzofurans (PCDD/DFs, dioxins) and coplanar polychlorinated biphenyls in environmental samples is developed and used to determine the levels of PCDD/DFs in 13 soil and 4 fish samples collected around a waste pentachlorophenol manufacturing plant. The 2,3,7,8‐tetrachlorodioxin toxic equivalents (TEQ) values range from 0.239 ng‐TEQ/g to 1357 ng‐TEQ/g in soil samples and 0.041 ng‐TEQ/g to 0.247 ng‐TEQ/g in fish samples. A broader survey of PCDD/DF contamination in the vicinity around the manufacturing plant is strongly recommended.
Determination of Bismuth in Sediment and Soil by Ultrasonic Slurry Sampling Electrothermal Atomic Absorption Spectrometry
Authors: Mierzwa J. , Sun Y. C. , Yang M. H. 
Published: May 2015

AbstractThe analytical conditions of the direct determination of bismuth in some certified reference material samples (soil and sediment) by slurry sampling Zeeman electrothermal atomic absorption spectrometry (ETAAS) with the use of automated ultrasonic slurry mixing are discussed. Palladium nitrate was used as a chemical modifier. With the use of this modifier it was possible to stabilize bismuth to the pyrolysis temperature of 1300 °C. Platform atomization was performed at 2050 °C. The results of determination are calculated from a simple, aqueous standards based calibration graph.Statistical evaluation of the results indicate that the slurry sampling method is reproducible and the accuracy of the proposed method is very good. This method is rather simple and its other advantages are good sensitivity and relatively short analysis time.
Selenium Determination in Serum by Graphite Furnace Atomic Absorption Spectrometry
Authors: Yen Cheng‐Chieh , Chen Wen‐Kang , Wang Chin‐Ping , You Jiing‐Nar , You Wei‐Chu , Yu Jya‐Jyun , Lee Yean‐Jang , Chung Chien , Kuo Sheng‐Chu 
Published: May 2015

AbstractSelenium concentration in serum has been proposed as the most valuable indicator of human selenium status. In this work, the concentration of selenium in serum is measured by GFAAS using longitudinal Zeeman‐effect background correction, a highly sensitive technique that can be used to determine selenium at sub‐ppb level. Standard reference materials are analyzed to verify the accuracy and precision of this technique. The direct method proposed in this study is used for the determination of selenium in human serum collected from healthy people of 19–25 years and women of 21–34 years in the First trimester of pregnancy. The method developed in this study, which can quickly and accurately measure serum selenium, is suitable for applications in clinical diagnosis or biological monitoring.
Synthesis and Characterizations of p‐Xylyl Bridged Dinuclear Complexes of Molybdenum and Tungsten. The Crystal Structure of μ‐p‐xylyl‐bis(1‐Me‐3‐SiMe3‐cyclopentadienyltricarbonylmolybdenum)
Authors: Lin See , Chen Yen‐Hsien 
Published: May 2015

AbstractThe reactions of R1R2CpM(CO)3−Li+ (M = Mo, W) with α, α′‐dichloro‐p‐xylene yielded p‐xylyl bridged dinuclear complexes of R1R2CpM(CO)3 in high yields. All of such new complexes are very stable to air and water. Some of them are stable even in dilute acids and dilute bases. Complex 4 crystallizes in the monoclinic system, space group P21/n, with a = 6.847(5) Å, b = 9.838(2) Å, c = 25.140(10) Å, β = 96.56(5)°, Z = 2, RF=0.077, Rw = 0.105 and V = 1682.4(14) Å3.
Syntheses of New Azo Dyestuff Containing a Sydnone Ring
Authors: Tien Hsien‐Ju , Hwang Yuh‐Ren , Wen Ten‐Chin 
Published: May 2015

AbstractNew azo dyestuffs containing a sydnone ring were prepared by the diazonium coupling of 3‐(p‐/m‐aminophenyl)sydnones with phenol or 1‐/2‐naphthols.
Photophysics of Indocarbocyanine Dyes in Organic Solvents
Authors: Zhifei Dai , Bixian Peng 
Published: May 2015

AbstractThe absorption and fluorescence properties of a series of 18 indocarbocyanine dyes in organic solvents have been determined. The wavelengths of the absorption and fluorescence maxima, the fluorescence lifetimes and the fluorescence quantum yields relative to the benzo‐15‐crown‐5‐substituted phthalocyanine have been measured. The results are discussed in relation to the molecular structures or the dye studied.
NMR Study of the Ligand Interchange of Hexacyclen and Hexamethylhexacyclen Complexes with TI+ Ion in 70% Methanol Solution
Authors: Shamsipur Mojtaba , Alizadeh Naader 
Published: May 2015

AbstractThe exchange kinetics of TI+ complexes with hexacyclen and hexamethylhexacyclen were studied in 70% methanol solution by proton NMR line‐shape analysis. In TI+‐hexacyclen system, a dissociative mechanism is found to be predominant at higher temperatures, while a bimolecular pathway may become more important at lower temperatures. In contrast, the TI+‐hexamethylhexacyclen system solely prefers a dissociative exchange mechanism in entire temperature range studied. The corresponding exchange rates and the activation parameters Ea, ΔH‡, ΔS‡ and ΔG‡ for the exchange have been determined, and the possible parameters controlling the exchange rates and mechanisms are discussed.
New Triterpenes from the Heartwood of Melaleuca leucadendron L.
Authors: Lee Ching‐Kuo 
Published: May 2015

AbstractFourteen chemical constituents were isolated from the CHCl3 soluble portion of the heartwood of Melaleuca leucadendron L. These compounds include β‐sitosterol (1), β‐sitostenone (2), 6‐hydroxy‐4,6‐dimethyl‐3‐hepten‐2‐one (3), naphthalene (4), squalene (5), 2α3β‐dihydroxyurs‐12‐en‐28‐oic acid (6), 3β‐hydroxylup‐20(29)‐en‐27,28‐dioic acid (7), 2α,3β‐dihydroxyolean‐12‐en‐28‐oic acid (8), 3β,23‐dihydroxyolean‐12‐en‐28‐oic acid (9), 2α,3β,23‐trihydroxyolean‐12‐en‐28‐oic acid (10), 3β‐trans‐p‐coumaroyloxy‐2α,23‐dihydroxyolean‐12‐en‐28‐oic acid (11), and three novel oleanane derivatives 23‐trans‐p‐coumaroyloxy‐2α,3β‐dihydroxyotean‐12‐en‐28‐oic acid (12), 3β‐trans‐caffeoyloxy‐2α,23‐dihydroxyolean‐12‐en‐28‐oic acid (13), and its isomer 3β‐cis‐caffeoyloxy‐2α,23‐dihydroxyolean‐12‐en‐28‐oic acid (14), The three novel compounds were characterized as the two and three O‐methylated derivatives, respectively.
Photochemistry of p‐Nitroacetophenone in 2‐Propanol
Authors: Lin Yuh‐Nong , Jeng Guang‐Yan , Chan Tung‐Tan , Yen Giann‐Feng , Wong Yin‐Gang 
Published: May 2015

AbstractUpon irradiation in 2‐propanol, p‐nitroacetophenone 1 was reduced via the triplet state to p‐hydroxyaminoacetophenone 5 which was further reduced to p‐aminoacelophenone 2 and 4,4′‐diacetylazobenzene 4. Similar irradiation of 5 also gave 2 and 4, and its oxidation by oxygen gave 4,4′‐diacetylazoxybenzene 3. Photolysis of monomeric p‐nitrosoacetophenone 6 afforded acetophenone and 3 that were not produced during the irradiation of 1. Possible photoreaction pathways were discussed on the basis of published mechanisms.
Tandem Thermal Reactions for the Synthesis of Jasmonoids
Authors: Ho Tse‐Lok , Shyu Kuo‐Feng 
Published: May 2015

AbstractA tandem reaction tactic for the preparation of a jasmonoid intermediate consists of pyrolysis of a spiroannulated cyclopentanone. The thermal decomposition actually involves a retro‐Diels‐Alder reaction and a homo‐1,5‐hydrogen shift with cleavage of the cyclopropane unit.
Intramolecular Electronic Energy Transfer in a Supersonic Jet Expansion
Authors: Speiser Shammai 
Published: May 2015

AbstractIntramolecular electronic energy transfer (intra‐EET) was investigated in an isolated bichromophoric naphthalene (N) and anthracene (A) 1:1 molecular cluster. Investigation of the spectroscopic properties of these chromophores, separately and loosely bound in a van der Waals complex, helps to understand the dependence of the EET rate on the initially excited vibronic level and on the cluster's interchromophoric orientation.Measurement of fluorescence excitation spectra of anthracene, at different anthracene pressures shows bands that can be assigned to dimers of anthracene. From measurement of the anthracene excitation spectrum at increasing naphthalene pressures one can identify other spectral features, characterized by different spectral shifts from excitations of the bare molecule. Some transitions are probably due to a 13.5 cm−1 progression associated with an interchromophore cluster bond. Pressure dependence of fluorescence intensity gives evidence for 1:1 cluster composition, and for a slow intra‐EET rate that is associated with an unfavoured orientation of the two chromophores in one of the two possible conformers of the A‐N cluster, as supported by a calculation of the cluster geometry and by comparison with a recent study of intra‐EET in the A‐(CH2)n‐N bichromophoric molecules.
Acid‐Base Properties of the Ground and Excited States of Ruthenium(II) Tris(4′‐methyl‐2,2′‐bipyridine‐4‐carboxylic Acid)
Authors: Su Chien‐Hua , Chang I‐Jy 
Published: May 2015

AbstractThe acid dissociation constant, pKa, for the ground and excited states of ruthenium tris(4′‐methyl‐2,2′‐bipyridine‐4‐carboxylic acid) complex have been measured. The ground state pKa obtained from the pH titration curve of the complex absorption at 454 nm was 2.5. The lifetimes of the excited‐state for deprotonated and protonated ruthenium complexes are 595 and 150 ns, respectively. The excited‐state pKa* is obtained from the emission titration curve at 630 nm and corrected for the excited‐state lifetime to be 4.2. The increase of 1.7 pH units in the acid dissociation constant in the excited‐state indicates that the ligand is much more basic in the excited‐state. This result confirms the MLCT assignment for the lowest electronic transition of [Ru(mbpyCOOH)3]2+.
Synthesis, Structure and Magnetic Properties of a Cyclic Heterotetranuclear Co3Fe Complex of 2‐Mercaptophenol (H2mp) with tri‐n‐Butylphosphine Participation
Authors: Chen Zhong‐Ning , Li Wen‐Jie , Rang Bei‐Sheng , Zhang Hua‐Xin , Zhou Zhong‐Yuan , Mak Thomas C. W. , Cai Yuan‐Ba , Hong Mao‐Chun , Liu Han‐Qin 
Published: May 2015

AbstractNeutral heterotetranuclear complex Co3Fe(mp)4(Hmp)(PBun3)3 2 (PBun3 = tri‐n‐butylphosphine) of 2‐mercaptophenol (H2mp) was synthesized in a molar ratio of CoCl2:FeCl3:H2mp:NaOMe:PBun3 = 0.75:0.25:1:2:1 under anaerobic conditions. It represents partially FeIII‐substituted form of the asymmetric mixed‐valence tetracobalt complex Co4(mp)4(Hmp)(PBun3)3 (1). 2 crystallizes in the triclinic space group Pl̄, with a = 12.373(2) Å, b = 15.677(3) Å, c = 20.571(4) Å, α = 93.59(3)° β = 93.45(3)° γ = 112.30(3)°, V = 3669 Å3, and Z = 2. The molecule exhibits a cyclic skeleton of Co3FeS4O3 with two doubly μ2‐S bridges, one doubly μ2‐O bridge, and one singly μ2‐O bridge. The four mp2− ligands display two different modes, ObSb‐T and OtSb, while the monoanion Hmp− is only terminally chelated to Fe3+ ion in HOtSt fashion (b stands for bridge, t for terminal, and T for trinuclear). The three Co centers are located in approximately square‐based pyramidal environments, and the Fe atom in distorted trigonal bipyramidal geometry. Three types of main fragment ions were observed in the FAB mass spectrum of 2. The dissociation of the fragments follows the order: PBun3 first, then Hmp and mp ligands. Moreover, the dissociation of Fe(Hmp) is first, followed by Co(mp) and Co(mp)2, according with the fact that Fe(Hmp) is only loosely bonded. Variable‐temperature magnetic susceptibility measurements showed that 2 exhibits weak magnetic exchange interactions.
Synthesis and Reactivities of 1,5‐ and 1,7‐Azulenequinone Derivatives. A Highly Convenient, One‐Pot Synthesis of 3‐Bromo‐1,5‐ and −1,7‐Azulenequinones by Bromination of Azulene,
Authors: Wakabayashi Hidetsugu , Kurihara Teruo , Shindo Kimio , Tsukada Masaaki , Yang Paw‐Wang , Yasunami Masafumi , Nozoe Tetsuo 
Published: May 2015

AbstractA very convenient, one‐pot synthesis (over 80% yield) of 3‐bromo‐1,5‐ and −1,7‐azulenequinones has been developed by bromination of azulene in aqueous tetrahydrofuran. Reduction of 3‐bromo‐1,5‐ and −1,7‐azulenequinones with tin or zinc powder in acetic acid gave the parent 1,5‐ and 1,7‐azulenequinones, and further reduction products.
“Sock‐Ball” Chromatographic Separation of Some Polycyclic Aromatic Hydrocarbons with C60‐Fullerene Stationary Phase
Authors: Chang Cheng‐Shyong , Tsai Hou‐Jen , Den Tschau‐Gan 
Published: May 2015

AbstractPolycyclic aromatic hydrocarbons (PAHs) of different molecular shapes were tested and compared with a prepared C60‐fullerene‐phase, and with the commercial Amino‐phase or RP‐18‐phase in the mobile phase of methanol/dichloromethane (90/10 — 70/30) or n‐hexane/dichloromethane (80/20). The chromatographic separation results indicate that C60‐fullerene‐phase achieves the special selectivities and performances for the separation of PAHs. Based on the retention mechanism of “π‐π” complex interaction or “Sock‐Ball” shaped combination, PAHs undergo more pronounced interaction with C60 ligand. For example, decacyclene, a sock‐shaped PAH, the structure of which was calculated by means of semi‐empirical molecular orbital methods, possesses stronger retention to give a “Sock‐Ball” chromatographic separation with C60‐fullerene‐phase. However, PAHs with bend, planar, or co‐planar structures eluted on C60‐fullerene‐phase undergo adsorption chromatography, but possess weaker retentions. The retention power of “Sock‐Ball” chromatography can successfully recognize the different molecular shapes of PAHs.
Aggregative Activation in Connection with a Few Reactions Using Transition or Alkali Metal Derivatives as Intermediates
Authors: Caubère Paul 
Published: May 2015

AbstractAggregative Activation principles are given. The first application described deals with the preparation of reducing agents used to perform couplings and carbonylations of aryl and hetaryl halides. The second application deals with the preparation of two kind of super bases: sodium amide and butyllithium containing complex bases. The arynic synthesis of indoles is given as an illustration of the use of the first kind of base while the metalation of pyridine derivatives exemplifies the use of the second. In this latter case, a new metalation radical mechanism is proposed.
Interaction of T1 and S1 States of h4‐ and d4‐Acetaldehyde Using a Quantum‐Beat Technique
Authors: Hsu Tsing‐Jung , Lee Shih‐Huang , Tang Kuo‐Chun , Chen I‐Chia 
Published: May 2015

AbstractDecays of fluorescence of h4‐ and d4‐acetaldehyde are measured. The quantum‐beat structure is observed for both isotopic species. This oscillatory phenomenon is due to interaction of the state S1 (Ã′ A″) and T1. Below the dissociation threshold to form products methyl and formyl radicals, an upper limit of a lifetime is set at 195‐800 ns for perturbed triplet states of CD3CDO; the lifetime is calculated directly from the linewidth of Fourier‐transformed spectra. At excitation wavelength shorter than 316.12 nm, the transformed linewidth increases, indicating the onset of CD3 + DCO formation.
Synthesis and Structures of 1‐(2‐Thienylmethyl)‐2‐(2‐thienyl)bezimidazole and Its Cu(I) and Ag(I) Complexes
Authors: Hwang Wen‐Shu , Hwang Chung‐Jeh , Wang Dong‐Liang , Lee Liang‐Shiu , Chiang Michael Y. 
Published: May 2015

AbstractN,N′‐1,2‐phenylenebis(2‐thienylideneimine) (PTI) can be obtained via the condensation of o‐phenylenediamine and thiophene‐2‐carboxaldhyde in cyclohexane. It isomerized to its cyclic form 1‐(2‐thienylmethyl)‐2‐(2‐thienyl)benzimidazole (TMTBI) readily in the presence of Fe2(CO)9. Coordination reactions of PTI with cuprous iodide and silver nitrate in acetonitrile resulted in the formation of [Cu(TMTBI)I]2 and [Ag(TMTBI)2]NO3, respectively, in which the PTI ligand had been isomerized to TMTBI. Both PTI, TMTBI, and complexes were characterized by NMR, IR, and Mass spectroscopies as well as elemental analysis. The crystal structures of TMTBI and [Cu(TMTBI)I]2 were determined by single‐crystal X‐ray diffraction. Crystallographic details for X‐ray structures are as follows. TMTBI is crystallized in the monoclinic space group P21/n with a = 8.953(3), b = 9.150(1), c = 17.436(2) Å, β = 93.73(2)°, and Z = 4. The final R factor was 0.050 (Rw = 0.066) for 1337 observed reflections. Complex [Cu(TMTBI)I]2 is crystallized in the triclinic space group \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm P}\bar 1 $\end{document} with a = 9.961 (2), b = 10.825(2), c = 9.184(2) Å, α = 112.98(2), β = 110.78(2), γ = 88.71 (2)°, and Z = 2. The final R factor was 0.056 (Rw = 0.057) for 2363 observed reflections.
Purification, Characterization and Mechanistic Study of β‐Glucosidase from Flavobacterium meningosepticum (ATCC 13253)
Authors: Li Yaw‐Kuen , Chu Shi‐Her , Sung Yu‐Hui 
Published: May 2015

AbstractA β‐glucosidase (EC 3.2.1.21) from Flavobacterium meningosepticum has been purified and characterized. Purity was enhanced at least 530‐fold from crude cell extract with 16.6% yield. The estimated molecular mass of the purified enzyme is 150 kDa by gel filtration and 78 kDa by SDS‐PAGE. This dimeric enzyme has a pI = 9.0 and an optimal activity at pH 5.0 and temperature of 50 °C. Divalent metal ions (Hg2+, Cu2+, Ca2+, Mg2+) and EDTA have negligible effect on the enzyme activity. The enzyme exhibited a high specificity on the glycon portion of aryl‐β‐D‐glycosides. NMR spectroscopy revealed the enzyme catalyzed hydrolysis of p‐nitrophenyl‐β‐D‐glucopyranoside with the retention of anomeric configuration, indicating that a double displacement mechanism was involved. A preliminary study of the Bronsted relationship showed a concave‐downward plot, which is consistent with the two‐step mechanism.