Affinity partitioning of a Cellulomonas fimi beta-mannanase with a mannan-binding module in galactomannan/starch aqueous two-phase system

A new approach in affinity separations was studied by partitioning of Cellulomonas fimi beta-mannanase (EC 3.2.1.78) containing a mannan-binding module in galactomannan/hydroxypropyl starch aqueous two-phase system. Comparison was made with a truncated version of C. fimi beta-mannanase which lacked the mannan-binding module. Results showed that affinity partitioning of the beta-mannanase was achieved due to biospecificity of the mannan-binding module towards the top phase containing galactomannan. Experiments were conducted at pH 8 to prevent enzyme degradation of the phase containing galactomannan. Removal of the top phase polymer was accomplished by beta-mannanase degradation allowed by shifting to the optimal pH 6. In the combination with the genetic fusion of any given protein to the mannan-binding module, the results envision a general procedure for primary affinity recovery of such fusion proteins.     

Interaction of quinapril anion with cationic surfactant micelles of cetyltrimethylammonium bromide

In this study, the interaction of the anion of quinapril (QUIN), angiotensin converting enzyme (ACE) inhibitor, with cationic surfactant cetyltrimethylammonium bromide (CTAB) was investigated. The effect of cationic micelles on the spectroscopic and acid-base properties of QUIN was studied at pH 8. The binding of QUIN anion to CTAB micelles implied a shift in drug acidity constant (pK(a)(water)-pK(a)(micelle)=1.39) proving the great affinity of negatively charged QUIN ion for the positively charged CTAB micelle surface. The strong dependence of the partition coefficient K(x) on QUIN concentration, obtained by using pseudo-phase model, is consistent with an adsorption-like phenomenon. From the dependence of differential absorbance at lambda=272 nm on CTAB concentration, by using mathematical model that treats the solubilization of QUIN anion as its binding to specific sites in the micelles (Langmuir adsorption isotherm), the binding constant K(b)=(2.3+/-0.4)x10(3) mol(-1)dm(3) was obtained. QUIN-CTAB binding constant was also calculated from micellar liquid chromatography (MLC) and this method was found to be not accurate enough for its determination.     

Automerization reaction of cyclobutadiene and its barrier height: an ab initio benchmark multireference average-quadratic coupled cluster study

The problem of the double bond flipping interconversion of the two equivalent ground state structures of cyclobutadiene (CBD) is addressed at the multireference average-quadratic coupled cluster level of theory, which is capable of optimizing the structural parameters of the ground, transition, and excited states on an equal footing. The barrier height involving both the electronic and zero-point vibrational energy contributions is 6.3 kcal mol(-1), which is higher than the best earlier theoretical estimate of 4.0 kcal mol(-1). This result is confirmed by including into the reference space the orbitals of the CC sigma bonds beyond the standard pi orbital space. It places the present value into the middle of the range of the measured data (1.6-10 kcal mol(-1)). An adiabatic singlet-triplet energy gap of 7.4 kcal mol(-1) between the transition state (1)B(tg) and the first triplet (3)A(2g) state is obtained. A low barrier height for the CBD automerization and a small DeltaE((3)A(2g),(1)B(1g)) gap bear some relevance on the highly pronounced reactivity of CBD, which is briefly discussed.     

Nonlinear Parabolic Equations with Regularized Derivatives in Colombeau Algebra

We consider several types of nonlinear parabolic equations with singular like potential and initial data. To prove the existence-uniqueness theorems we employ regularized derivatives. As a framework we use Colombeau space and Colombeau vector space      

Intraspecific Diversity within <Emphasis Type="Italic">Ganoderma lucidum</Emphasis> in the Production of Laccase and Mn-Oxidizing Peroxidases During Plant Residues Fermentation

Comparison of the potential for laccase and Mn-oxidizing peroxidases synthesis by ten strains of Ganoderma lucidum, originating from different worldwide areas, during solid-state fermentation of selected plant raw materials was the aim of this study. The great intraspecific variability in the production of analyzed enzymes as well as the dependence of the enzyme activity on plant raw materials were reported. The strain HAI 957 was the best laccase producer in the presence of corn stem, as a unique carbon source (129.46 U/L). The highest level of Mn-dependent peroxidase activity was noted after wheat straw fermentation by G. lucidum HAI 246 (78.64 U/L), while the maximal versatile peroxidase production (59.72 U/L) was observed in strain HAI 957 in the medium with oak sawdust.     

Generalized Arago–Fresnel laws: the EME-flow-line description

We study experimentally and theoretically the influence of light polarization on the interference patterns behind a diffracting grating. Different states of polarization and configurations are considered. The experiments are analyzed in terms of electromagnetic energy (EME) flow lines, which can be eventually identified with the paths followed by photons. This gives rise to a novel trajectory interpretation of the Arago–Fresnel laws for polarized light, which we compare with interpretations based on the concept of “which-way” (or “which-slit”) information.     

Synthesis and biological evaluation of two novel 2′-substituted tiazofurin analogues

Two novel tiazofurin analogues, 2-(2-benzamido-2-deoxy-β-d-ribofuranosyl)thiazole-4-carboxamide 4 and 2-(2-azido-2-deoxy-β-d-ribofuranosyl)thiazole-4-carboxamide 5, have been synthesized starting from d-glucose and evaluated for their in vitro cytotoxicity against several human leukaemia and solid tumour cell lines.     

A theoretical study of the acetylide anion, HCC−

The results of various ab initio calculations are reported for the electronic ground state of the acetylide anion. An “Eyring's lake” in the T-shaped configuration is identified with six different methods (SCF, MP2, CCSD, CCSD-T, CCSD(T), and CEPA–1). The equilibrium bond lengths of HCC⁻ are estimated to be r _e (CH)=1.0689(3) ? and R _e (CC)=1.2464(2) ?, and the ground-state rotational constant is predicted to be B ₀=41636(20)MHz. The large permanent dipole moment of μ₀=−3.093D should facilitate detection of the anion by microwave spectroscopy. The band centers are predicted to be 3211.3cm⁻¹(ν₁), 511.1cm⁻¹(ν₂), and 1805.0cm⁻¹(ν₃). A large transition dipole moment of 0.477 D is calculated for the ν₂ band. Rovibrational levels of HCC⁻ up to approximately 20 000 cm⁻¹ above equilibrium are calculated with DVR-DGB and FBR methods on the basis of a previous CEPA–1 potential energy surface. Different energy patterns are found and discussed, for which anharmonic and Coriolis resonances are shown to play an important role. Received: 27 July 1998 Accepted: 12 August 1998 / Published online: 19 October 1998     

Laser doppler anemometry in hydrodynamic testing

Classical methods and the laser-Doppler-anemometry (LDA) application for the test section calibration of a water-cavitation tunnel is presented. The results show that the LDA is the best method for calibration and the classical methods satisfy the needs of standard tests. The advantages of the LDA are illustrated by determination of the pressure coefficient C _p for a hydrofoil of a high-speed axial pump under the stationary and nonstationary conditions, as well. The velocity vector distribution is measured around the central hydrofoil of a straight grid for angles of attack δ = 0° and 25° and undisturbed velocity v _∞ = 5.32 m/s. The results of the LDA measurements are used as a basis for the definition of the boundary conditions for numerical flow simulation and C _p calculation by the Fluent program. A flow visualization is made by aniline dyes and air bubbles.     

Three-Dimensional Lorentz Metrics and Curvature Homogeneity of Order One

In this paper we investigate the existence of three-dimensional Lorentzian manifolds which are curvature homogeneous up to order one but which are not locally homogeneous, and we obtain a complete local classification of these spaces. As a corollary we determine, for each Segre type of the Ricci curvature tensor, the smallest k N for which curvature homogeneity up to order k guarantees local homogeneity of the three-dimensional manifold under consideration.