Catalytic Properties of Two <Emphasis Type="Italic">Rhizopus oryzae</Emphasis> 99-880 Glucoamylase Enzymes Without Starch Binding Domains Expressed in <Emphasis Type="Italic">Pichia pastoris</Emphasis>

Catalytic properties of two glucoamylases, AmyC and AmyD, without starch binding domains from Rhizopus oryzae strain 99-880 are determined using heterologously expressed enzyme purified to homogeneity. AmyC and AmyD demonstrate pH optima of 5.5 and 6.0, respectively, nearly one unit higher than the Rhizopus AmyA glucoamylase enzyme. Optimal initial activities are at 60 and 50 °C for AmyC and AmyD, respectively. Inactivation of both enzymes occurs at 50 °C following 30 min pre-incubation. The two enzymes demonstrate substantially slower catalytic rates toward soluble starch relative to AmyA. AmyC has similar k _cat and K _m for oligosaccharides to other Rhizopus and Aspergillus glucoamylases; however, the enzyme has a 2-fold lower K _m ^maltose . AmyD has a 3-fold higher K _m and lower k _cat for maltooligosaccharides than AmyC and other glucoamylases. AmyC (but not AmyD) exhibits substrate inhibition. K _i for substrate inhibition decreases with increasing length of the oligosaccharides. Data from pre-steady-state binding of AmyC to maltose and maltotriose and pre-steady-state to steady-state catalytic turnover experiments of AmyC acting on maltotriose were used to interrogate models of substrate inhibition. In the preferred model, AmyC accumulates an enzyme-maltose-maltotriose dead-end complex in the steady state.     

Kinetics of Na|CF<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> and Li|CF<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> systems

Properties of CF _x /Li and CF _x /Na cells were examined while using galvanostatic charging/discharging, electrochemical impedance spectroscopy and scanning electron microscopy (SEM). The capacity during the first cycle was as high as ca. 1000 mAh g^?1. Such an electrode is suitable for primary CF _x /Li and CF _x /Na batteries. SEM images of CF _x cathode showed that during discharging it was transformed into amorphous carbon and LiF or NaF crystals (of diameter of ca. 5–20 μm). These systems (C?+?LiF or C?+?NaF) cannot be reversibly converted back into CF _x /Li or CF _x /Na, respectively. Exchange current densities are between 10^?7 Acm^?2 and 10^?9 Acm^?2 when working with LiPF₆ and NaPF₆ electrolytes (1.12?×?10^?7 Acm^?2 and 6.82?×?10^?9 Acm^?2, respectively). Those values are low and indicate that the charge transfer process may be the rate-determining step. Activation energies for the charge transfer process were 57 and 72 kJ mol^?1 for CF _x /LiPF₆ and CF _x /NaPF₆ systems, respectively. Higher activation energy barrier for the CF/Na⁺?+?e^??→?C?+?NaF reaction results in lower observed exchange current density in comparison to the system with lithium ions.     

Purification and Characterization of Agarase from Marine Bacteria <Emphasis Type="Italic">Acinetobacter</Emphasis> sp. PS12B and Its Use for Preparing Bioactive Hydrolysate from Agarophyte Red Seaweed <Emphasis Type="Italic">Gracilaria verrucosa</Emphasis>

Acinetobacter strain PS12B was isolated from marine sediment and was found to be a good candidate to degrade agar and produce agarase enzyme. The extracellular agarase enzyme from strain PS12B was purified by ammonium sulfate precipitation followed by DEAE-cellulose ion-exchange chromatography. The specific activity of the crude enzyme which was 1.52 U increased to 45.76 U, after two-stage purification, with an enzyme yield of 9.76%. Purified enzyme had a molecular mass of 24 kDa. The optimum pH and temperature for activity of purified agarase were found to be 8.0 and 40 °C, respectively. The K_m and V_max values for agarase were 4.69 mg/ml and 0.5 μmol/min, respectively. Treatment with EDTA reduced the agarase activity by 58% at 5 mM concentration. The enzyme activity was stimulated by the presence of Fe²⁺, Mn²⁺, and Ca2⁺ ions while reducing reagents (β-mercaptoethanol and dithiothreitol, DTT) enhanced its activity by 30–40%. The purified agarase exhibited tolerance to both detergents and organic solvents. Major hydrolysis products of agar were DP4 and also a mixture of longer oligosaccharides DP6 and DP7. The enzyme hydrolysed seaweed (Gracilaria verrucosa) exhibited strong antioxidant activity in vitro. Successful hydrolysis of seaweed indicates the potential use of the enzyme to produce seaweed hydrolysate having health benefits as well as the industrial application like the production of biofuels.     

Study of the growth of <Emphasis Type="Italic">Enterococcus faecalis</Emphasis>, <Emphasis Type="Italic">Escherichia coli</Emphasis> and their mixtures by microcalorimetry

In a majority of environments, microbes live as interacting communities. Microbial communities are composed of a mix of microbes with often unknown functions. Polymicrobial diseases represent the clinical and pathological manifestations induced by the presence of multiple infectious agents. These diseases are difficult to diagnose and treat and usually are more severe than monomicrobial infections. The interaction relationship between Enterococcus faecalis and Escherichia coli was researched using a Calvet calorimeter. Three mixtures of both bacteria were prepared in the following proportions: 20 + 80 % (0.2 mL E. faecalis + 0.8 mL E. coli), 50 + 50 % (0.5 mL E. faecalis + 0.5 mL E. coli) and 80 + 20 % (0.8 mL E. faecalis + 0.2 mL E. coli). Experiments were carried out at concentration of 10⁶ CFU mL^?1 and a constant temperature of 309.65 K. The differences in shape of graph of E. faecalis, E. coli and their mixtures were compared. Also, the thermokinetic parameters such as detection time (t _d), growth constant (k), generation time (G) and the amount of heat released (Q) were calculated.     

Purification and Characterization of a Naringinase from <Emphasis Type="Italic">Cryptococcus albidus</Emphasis>

Naringinase which was extracted from the fermented broth of Cryptococcus albidus was purified about 42-folds with yield 0.7% by sulfate fractionation and chromatography on Toyopearl HW-60, Fractogel DEAE-650-s, and Sepharose 6B columns. Molecular weight of protein determined by gel filtration and SDS-PAGE was 50 kDa. Naringinase of C. albidus includes high content of the dicarbonic and hydrophobic amino acids. Enzyme contains also carbohydrate component, represented by mannose, galactose, rhamnose, ribose, arabinose, xylose, and glucose. The enzyme was optimally active at pH 5.0 and 60 °C. Naringinase was found to exhibit specificity towards p-nitrophenyl-α-L-rhamnose, p-nitrophenyl-β-D-glucose, naringin, and neohesperidin. Its K _m towards naringin was 0.77 mM and the V _max was 36 U/mg. Naringinase was inhibited by high concentrations of reaction product—L-rhamnose. Enzyme revealed stability to 20% ethanol and 500 mM glucose in the reaction mixture that makes it possible to forecast its practical use in the food industry in the production of juices and wines.     

Purification and characterization of an extracellular lipolytic enzyme from the fermented fish-originated halotolerant bacterium, <Emphasis Type="Italic">Virgibacillus alimentarius</Emphasis> LBU20907

A halotolerant Virgibacillus alimentarius LBU20907 isolated from fermented fish (Budu) was found to be an efficient producer of extracellular halophilic lipase enzyme. The enzyme was purified 5.99-fold with a 0.15% final yield to homogeneity by ammonium sulfate precipitation, followed by dialysis, Toyopearl DEAE-650 M ion exchange chromatography, Toyopearl butyl-650 M hydrophobic interaction chromatography, and Toyopearl-HW 55 F gel filtration chromatography. SDS-PAGE of purified lipase exhibited a homogenous single band with a very high molecular weight of 100 kDa. The properties of purified lipase revealed maximum activity at pH 7.0 and 40 °C. It was also highly stable in a pH range of 6.0–7.0, retaining more than 90% activity for 24 h. It was stable at the temperature of 30–50 °C and maintained more than 80% activity for 16 h. The purified lipase performing the maximal activity in the presence of 20.0% NaCl indicated halophilic enzyme properties. Its lipolytic activity was highest against p-nitrophenyl palmitate. The lipase activity was found to be enhanced in hexane. The enzyme activity was stimulated in the presence of Zn²⁺, Ca²⁺, Mg²⁺, and Sr²⁺; while, it was completely inhibited by Ba²⁺ and Co²⁺. The enzyme had a K _m and V _max of 108.0 mg and 79.1 U mL^?1, respectively.     

Stability of <Emphasis Type="Italic">s</Emphasis>-, <Emphasis Type="Italic">p</Emphasis>-, and <Emphasis Type="Italic">d</Emphasis>-element diphosphates in water

The mean atomic Gibbs energies of formation of (Δ _f ? _at ⁰ ) of s-, p-, and d-element diphosphates have been calculated using ion increments of the Gibbs energy (Δ _f G ⁰). The diphosphate hydrolysis kinetics is considered, and a correlation between the Δ _f ? _at ⁰ values and the hydrolysis rate constants is presented.     

Crystallographic and conformational analysis of (<Emphasis Type="Italic">E</Emphasis>)-2-isopropyl-4-(<Emphasis Type="Italic">p</Emphasis>-tolyldiazenyl)phenol

The molecular and crystal structures of the title compound, C₁₆H₁₈N₂O, were characterized and determined by single crystal X-ray diffraction method in addition to spectroscopic means such as IR, UV–VIS and ¹H NMR. The compound crystallizes in orthorhombic space group P bca, with a = 9.3350(5) Å, b = 23.4878(13) Å, c = 26.5871(12) Å, Z = 16, D _calc. = 1.1591(1) g/cm³, μ (MoK_α) = 0.073 mm^?1. Monomers of the compound in the crystal structure are linked into C(7) and C(8) chains generated by translation along the [1 0 0] direction with the aid of O–H···N type H-bonds which serve to the stabilization of periodic organization of the molecules beside major and minor component in the disordered azo fragment. In order to describe conformational flexibility and the crystal packing effects on the molecular conformation, potential barriers regarding the rotation along both Ar–N bonds were calculated by varying the related torsional degrees of freedom in every 10° ranging from ?180° to +180° via quantum chemical calculations at DFT/B3LYP level.     

Purification of Histidine-Tagged Membrane-Bound Catechol-<Emphasis Type="Italic">O</Emphasis>-Methyltransferase from Detergent-Solubilized <Emphasis Type="Italic">Pichia pastoris</Emphasis> Membranes

Catechol-O-methyltransferase (COMT) is an enzyme involved in catecholamine catabolism that is key for the treatment of different neurologic disorders. Actually, there are still unmet needs concerning the development of more selective membrane-bound COMT (hMBCOMT) downstream strategies, envisaging their application in structural and bio-interaction studies. Therefore, in this work, recombinant hexahistidine-tagged hMBCOMT (hMBCOMT-His₆) was expressed from Pichia pastoris methanol-induced cultures in a catalytically active form (27.3 nmol h^?1 mg^?1 of protein) and successfully solubilized with n-dodecyl β-d-maltoside. Afterward, immobilized-metal affinity chromatography provided the required selectivity for the direct capture of hMBCOMT-His₆ from detergent-solubilized P. pastoris membranes, being the target enzyme recovered in a highly purified fraction. Also, despite the relatively low purification fold (1.53), the purity of the target enzyme assessed by SDS-PAGE is high and it is recovered with biological activity (67 nmol h^?1 mg^?1 of protein). Then, after a final polishing stage using Q-Sepharose, a pure and immunologically active enzyme fraction was obtained. Overall, the strategy herein reported may be applied to obtain pure hMBCOMT fractions, debottlenecking the implementation of bio-interaction studies and relieving the problems associated with hMBCOMT drug discovery pipeline. In a last analysis, these studies may lead to the establishment of new pharmacological therapies, thereby improving the prognosis of neurologic disorders.     

Production of <Emphasis Type="Italic">R</Emphasis>-Mandelic Acid Using Nitrilase from Recombinant <Emphasis Type="Italic">E. coli</Emphasis> Cells Immobilized with Tris(Hydroxymethyl)Phosphine

Recombinant Escherichia coli cells harboring nitrilase from Alcaligenes faecalis were immobilized using tris(hydroxymethyl)phosphine (THP) as the coupling agent. The optimal pH and temperature of the THP-immobilized cells were determined at pH 8.0 and 55 °C. The half-lives of THP-immobilized cells measured at 35, 40, and 50 °C were 1800, 965, and 163 h, respectively. The concentration of R-mandelic acid (R-MA) reached 358 mM after merely 1-h conversion by the immobilized cells with 500 mM R,S-mandelonitrile (R,S-MN), affording the highest productivity of 1307 g L^?1 day^?1 and the space-time productivity of 143.2 mmol L^?1 h^?1 g^?1. The immobilized cells with granular shape were successfully recycled for 60 batches using 100 mM R,S-MN as substrate at 40 °C with 64% of relative activity, suggesting that the immobilized E. coli cells obtained in this study are promising for the production of R-MA.     

Overproduction,Purification and Characterization of Adenylate Deaminase from <Emphasis Type="Italic">Aspergillus oryzae</Emphasis>

Adenylate deaminase (AMPD, EC 3.5.4.6) is an aminohydrolase that widely used in the food and medicine industries. In this study, the gene encoding Aspergillus oryzae AMPD was cloned and expressed in Escherichia coli. Induction with 0.75 mM isopropyl β-d-l-thiogalactopyranoside resulted in an enzyme activity of 1773.9 U/mL. Recombinant AMPD was purified to electrophoretic homogeneity using nickel affinity chromatography, and its molecular weight was calculated as 78.6 kDa. Purified AMPD exhibited maximal activity at 35 °C, pH 6.0 and 30 mM K⁺, with apparent K _m and V _max values of 2.7 × 10^?4 M and 77.5 μmol/mg/min under these conditions. HPLC revealed that recombinant AMPD could effectively catalyse the synthesis of inosine-5′-monophosphate (IMP) with minimal by-products, indicating high specificity and suggesting that it could prove useful for IMP production.     

Synthesis,spectroscopic characterization,crystal structures,and theoretical studies of (<Emphasis Type="Italic">E</Emphasis>)-2-(2,4-dimethoxybenzylidene)thiosemicarbazone and (<Emphasis Type="Italic">E</Emphasis>)-2-(2,5-dimethoxybenzylidene)thiosemicarbazone

Two thiosemicarbazones, (E)-2-(2,4-dimethoxybenzylidene)thiosemicarbazone (24-MBTSC (1)) and (E)-2-(2,5-dimethoxybenzylidene)thiosemicarbazone (25-MBTSC (2)), derived from 2,4-dimethoxybenzaldehyde and 2,5-dimethoxybenzaldehyde, respectively, with thiosemicarbazide have been synthesized and their structures were characterized by elemental analyses, FT-IR, ¹H NMR spectroscopy, and X-ray single-crystal diffraction analysis. Molecular orbital calculations have been carried out for 1 and 2 by using an ab initio method (HF) and also density functional method (B3LYP) at 6-31G basis set. Compound 1 crystallizes in the monoclinic system, space group P2₁/c, with a = 8.1342(5) Å, b = 18.1406(10) Å, c = 8.2847(6) Å, β = 109.7258(17)°, V = 1150.75(12) Å³, and Z = 4, whereas compound 2 crystallizes in the orthorhombic system, space group Pbca, with a = 11.0868(6) Å, b = 13.1332(6) Å, c = 15.9006(8) Å, V = 2315.2(2) Å³, and Z = 8. The compounds 1 and 2 displays a trans-configuration about the C=N double bond.     

Secondary self-assembly behaviors of PEO-<Emphasis Type="Italic">b</Emphasis>-P<Emphasis Type="Italic">t</Emphasis>BA-<Emphasis Type="Italic">b</Emphasis>-PS triblock terpolymers in solution

A series of PEO₄₅-b-PtBA₅₃-b-PS _x (x = 42, 84, 165) triblock terpolymers were synthesized by the atom transfer radical polymerization and characterized by size exclusion chromatography and ¹H NMR. Their self-assemblies were conducted by a two-step hierarchical self-assembly method and a one-step dialysis method and the self-assembly behaviors were investigated. The morphologies, sizes, and size distributions of micelles produced by the self-assembly were determined by transmission electron microscopy and dynamic light scattering. The secondary self-assembled structure of PEO₄₅-b-PtBA₅₃-b-PS _x obtained by the two-step hierarchical self-assembly could be controlled by tuning the length of PS block, the core forming block. The micelles were uniform with diameters of 20–25 nm and their size distributions, except for that of PEO₄₅-b-PtBA₅₃-b-PS₁₆₅, were narrow with particle size distribution indexes ranging from 0.014 to 0.246. The one-step dialysis of the triblock terpolymers produced vesicular micelles with distinct vesicle walls that exhibited similar thicknesses. The vesicles did not show significant aggregation. The size distribution of PEO₄₅-b-PtBA₅₃-b-PS₄₂ vesicle was the narrowest with a particle size distribution index value of 0.135. The PEO₄₅-b-PtBA₅₃-b-PS₁₆₅ vesicles tended to overlap with each other.     

CO<Subscript>2</Subscript> Biofixation and Growth Kinetics of <Emphasis Type="Italic">Chlorella vulgaris</Emphasis> and <Emphasis Type="Italic">Nannochloropsis gaditana</Emphasis>

CO₂ biofixation was investigated using tubular bioreactors (15 and 1.5 l) either in the presence of green algae Chlorella vulgaris or Nannochloropsis gaditana. The cultivation was carried out in the following conditions: temperature of 25 °C, inlet-CO₂ of 4 and 8 vol%, and artificial light enhancing photosynthesis. Higher biofixation were observed in 8 vol% CO₂ concentration for both microalgae cultures than in 4 vol%. Characteristic process parameters such as productivity, CO₂ fixation, and kinetic rate coefficient were determined and discussed. Simplified and advanced methods for determination of CO₂ fixation were compared. In a simplified method, it is assumed that 1 kg of produced biomass equals 1.88 kg recycled CO₂. Advance method is based on empirical results of the present study (formula with carbon content in biomass). It was observed that application of the simplified method can generate large errors, especially if the biomass contains a relatively low amount of carbon. N. gaditana is the recommended species for CO₂ removal due to a high biofixation rate—more than 1.7 g/l/day. On day 10 of cultivation, the cell concentration was more than 1.7?×?10⁷ cells/ml. In the case of C. vulgaris, the maximal biofixation rate and cell concentration did not exceed 1.4 g/l/day and 1.3?×?10⁷ cells/ml, respectively.     

Cotton Stalk Pretreatment Using <Emphasis Type="Italic">Daedalea flavida</Emphasis>, <Emphasis Type="Italic">Phlebia radiata</Emphasis>, and <Emphasis Type="Italic">Flavodon flavus</Emphasis>: Lignin Degradation,Cellulose Recovery,and Enzymatic Saccharification

Lignocellulolytic enzyme activities of selective fungi Daedalea flavida MTCC 145 (DF-2), Phlebia radiata MTCC 2791 (PR), and non-selective fungus Flavodon flavus MTCC 168 (FF) were studied for pretreatment of cotton stalks. Simultaneous productions of high LiP and laccase activities by DF-2 during early phase of growth were effective for lignin degradation 27.83 ± 1.25 % (w/w of lignin) in 20-day pretreatment. Production of high MnP activity without laccase in the early growth phase of PR was ineffective and delayed lignin degradation 24.93 ± 1.53 % in 25 days due to laccase production at later phase. With no LiP activity, low activities of MnP and laccase by FF yielded poor lignin degradation 15.09 ± 0.6 % in 20 days. Xylanase was predominant cellulolytic enzyme produced by DF-2, resulting hemicellulose as main carbon and energy source with 83 % of cellulose recovery after 40 days of pretreatment. The glucose yield improved more than two fold from 20-day DF-2 pretreated cotton stalks after enzymatic saccharification.     

Solution Thermodynamics of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis><Superscript>/</Superscript>-Ethylenebis-(salicylideneiminato)-diaquochromium(III) Chloride in Aqueous Dimethylsulphoxide

The densities, viscosities and refractive indices of N,N ^/-ethylene-bis(salicylideneiminato)-diaquochromium(III) chloride, [Cr(salen)(H₂O)₂]Cl, in aqueous dimethylsulfoxide (DMSO) with different mass fractions (w ₂ = 0.20, 0.40, 0.60, 0.80 and 1.00) of DMSO were determined at 298.15, 308.15 and 318.15 K under atmospheric pressure. From measured densities, viscosities and refractive indices the apparent molar volumes (V _φ ), standard partial molar volume (V _φ ⁰ ), the slope (S _V ^* ), standard isobaric partial molar expansibility (φ _E ⁰ ) and its temperature dependence (?φ _E ⁰ /?T) _p , the viscosity B-coefficient, its temperature dependence (?B/?T), solvation number (S _n ) and apparent molar refractivity (R _D ^φ ), etc., were calculated and discussed on the basis of ion–ion and ion–solvent interactions. These results revealed that the solutions are characterized by ion–solvent interactions rather than by ion–ion interactions and the complex behaves as a long range structure maker. Thermodynamics of viscous flow was discussed in terms of transition state theory.     

Direct electrochemistry and electrocatalysis of cytochrome <Emphasis Type="Italic">c</Emphasis> based on dandelion-like Bi<Subscript>2</Subscript>S<Subscript>3</Subscript> nanoflowers

The direct electrochemistry and electrocatalysis of cytochrome c (Cyt c) based on dandelion-like bismuth sulfide (d-Bi₂S₃) nanoflowers have been developed. The morphologies and composition of the d-Bi₂S₃ were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). Then, the electrochemical behaviors of Cyt c immobilized within the d-Bi₂S₃/chitosan film and its electrocatalytic ability toward hydrogen peroxide (H₂O₂) reduction were investigated by cyclic voltammetry. The electron transfer rate constant was estimated to be 13.1 s^?1, suggesting that a fast direct electron transfer was realized. The prepared Cyt c/d-Bi₂S₃/chitosan nanobiocomposite-modified electrode possessed excellent electrocatalytic ability toward H₂O₂ reduction that showed linearity in the range from 0.5 μM to 1.56 mM with a correlation coefficient of 0.9993. The detection limit was 0.2 μM on signal-to-noise ratio of 3. In addition, the d-Bi₂S₃ nanoflowers may be also applied to direct electron transfer of other redox proteins.     

Physical and Covalent Immobilization of <Emphasis Type="Italic">Lipase</Emphasis> onto Amine Groups Bearing Thiol-Ene Photocured Coatings

In this study, amine groups containing thiol-ene photocurable coating material for lipase immobilization were prepared. Lipase (EC 3.1.1.3) from Candida rugosa was immobilized onto the photocured coatings by physical adsorption and glutaraldehyde-activated covalent bonding methods, respectively. The catalytic efficiency of the immobilized and free enzymes was determined for the hydrolysis of p-nitrophenyl palmitate and also for the synthesis of p-nitrophenyl linoleate. The storage stability and the reusability of the immobilized enzyme and the effect of temperature and pH on the catalytic activities were also investigated. The optimum pH for free lipase and physically immobilized lipase was determined as 7.0, while it was found as 7.5 for the covalent immobilization. After immobilization, the optimum temperature increased from 37 °C (free lipase) to 50–55 °C. In the end of 15 repeated cycles, covalently bounded enzyme retained 60 and 70 % of its initial activities for hydrolytic and synthetic assays, respectively. While the physically bounded enzyme retained only 56 % of its hydrolytic activity and 67 % of its synthetic activity in the same cycle period. In the case of hydrolysis V _max values slightly decreased after immobilization. For synthetic assay, the V _max value for the covalently immobilized lipase was found as same as free lipase while it decreased dramatically for the physically immobilized lipase. Physically immobilized enzyme was found to be superior over covalent bonding in terms of enzyme loading capacity and optimum temperature and exhibited comparable re-use values and storage stability. Thus, a fast, easy, and less laborious method for lipase immobilization was developed.     

Characterization of Truncated <Emphasis Type="Italic">dsz</Emphasis> Operon Responsible for Dibenzothiophene Biodesulfurization in <Emphasis Type="Italic">Rhodococcus</Emphasis> sp. FUM94

Numerous desulfurizing bacteria from the Rhodococcus genus harbor conserved dsz genes responsible for the degradation of sulfur compounds through 4S pathway. This study describes a newly identified desulfurizing bacterium, Rhodococcus sp. FUM94, which unlike previously identified strains encodes a truncated dsz operon. DNA sequencing revealed a frameshift mutation in the dszA gene, which led to an alteration of 66 amino acids and deletion of other C-terminal 66 amino acids. The resulting DszA polypeptide was shorter than DszA in Rhodococcus sp. IGTS8 reference strain. Despite the truncation, desulfurizing activity of the operon was observed and attributed to the removal of an overlap of dszA and dszB genes, and lack of active site in the altered region. Desulfurization experiments resulted in specific production rate of 6.3 mmol 2-hydroxy biphenyl (kgDCW)^?1 h^?1 at 2 g l^?1 biocatalyst concentration and 68.8% biodesulfurization yield at 20 g l^?1 biocatalyst concentration, both at 271 μM dibenzothiophene concentration which is comparable to similar wild-type biocatalysts.     

Viscosities and Surface Tensions of Phenetole with <Emphasis Type="Italic">N</Emphasis>-Methyl-2-pyrrolidone, <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dimethylformamide and Tetrahydrofuran Binary Systems at Three Temperatures

Viscosities, η, and surface tensions, σ, of binary systems of phenetole (ethoxy benzene or ethyl phenyl ether) with N-methyl-2-pyrrolidone, N,N-dimethylformamide or with tetrahydrofuran were measured over the entire mole fraction range and at (298, 303 and 308) K. The experimental data was used to compute the deviations in viscosity, Δη, and surface tension, Δσ. Values of the excess Gibbs energy of activation G*^E, surface entropy S _σ and surface enthalpy H _σ were calculated. Viscosity data of the binary systems were calculated using the Grunberg and Nissan and the three-body and four-body McAllister correlations. The Redlich–Kister method was used for evaluation of coefficients and standard deviations for Δη, Δσ and G*^E. The results were interpreted in terms of the probable effect of molecular interactions between components as well as polarity.