Molecular and Spectroscopic Characterization of A<Emphasis Type="Italic">spergillus flavipes</Emphasis> and <Emphasis Type="Italic">Pseudomonas putida</Emphasis> L-Methionine γ-Lyase in Vitro

Pseudomonas putida L-methionine γ-lyase (PpMGL) has been recognized as an efficient anticancer agent, however, its antigenicity and stability remain as critical challenges for its clinical use. From our studies, Aspergillus flavipes L-methionine γ-lyase (AfMGL) displayed more affordable biochemical properties than PpMGL. Thus, the objective of this work was to comparatively assess the functional properties of AfMGL and PpMGL via stability of their internal aldimine linkage, tautomerism of pyridoxal 5′-phosphate (PLP) and structural stability responsive to physicochemical factors. The internal Schiff base of AfMGL and PpMGL have the same stability to hydroxylamine and human serum albumin. Acidic pHs resulted in strong cleavage of the internal Schiff base, inducing the unfolding of MGLs, compared to neutral-alkaline pHs. At λ 280 nm excitation, both AfMGL and PpMGL have identical fluorescence emission spectra at λ 335 nm for the intrinsic tryptophan and λ 560 nm for the internal Schiff base. The maximum PLP tautomeric shift of ketoenamine to enolimine was detected at acidic pH causing complete enzyme unfolding, subunits dissociation and tautomeric shift of intrinsic PLP, rather than neutral-alkaline ones. The T _m of AfMGL and PpMGL in presence of thermal stabilizer/ destabilizer was assayed by DSF. The T _m of AfMGL and PpMGL was 73.1 °C and 74.4 °C, respectively, suggesting the higher proximity to the tertiary structure of both enzymes. The T _m of AfMGL and PpMGL was slightly increased by trehalose and EDTA in contrast to guanidine HCl and urea. The active site and PLP-binding domains are identically conserved in both AfMGL and PpMGL.     

Convergence theorem for I-asymptotically quasi-nonexpansive mapping in Hilbert space

Let H be a Hilbert space with inner product (⋅,⋅) and ‖⋅‖ norm, and let K be weakly compact a subset of H. Let be nonlinear mapping and be a nonlinear bounded mapping. In this paper, we define the I-asymptotically quasi-nonexpansive mapping in Hilbert space. If T is an I-asymptotically quasi-nonexpansive mapping, then we prove that , for u∈K as n→∞, is weakly almost convergent to its asymptotic center.     

A Systematic Study on the Synthesis of n‐Butyl Substituted 8‐Aminoquinolines

A systematic study on the synthesis of 8‐aminoquinoline derivatives with an n‐butyl group at each alternate position of the quinoline ring was carried out. Skraup Reaction and its Doebner–von Miller variation were used to obtain most of the quinoline ring except for the 2‐butyl‐8‐aminoquinolines and 4‐butyl‐8‐aminoquinolines where the commercially available methylquinoline derivatives were used as precursors. The structures of the synthesized compounds were characterized by FTIR, ¹H‐NMR, COSY, ¹³C‐NMR and HRMS spectra.     

Solubilization of Cationic Hemicyanine Dyesin Anionic Surfactant Micelles: A Partitioning Study

Summary.  Cationic hemicyanine dyes of the 1-methyl-4-(4-(di-n-alkylamino)-styryl) pyridinium betain type (alkyl group=methyl to butyl) have been investigated by differential spectroscopy in order to ascertain their solubilization in aqueous micellar solution of sodium dodecylbenzene sulfonate (SDBS). The differential absorption spectra were recorded as a function of surfactant concentration at 25.0°C. Thermodynamic parameters were calculated from partition coefficient data. The results show that cationic hemicyanine dyes are solubilized at the micellar surface, indicating an electrostatic interaction between dyes and surfactant micelles. Received October 15, 1999. Accepted February 14, 2000     

Correlation Between the Scaling Factor of the Yukawa Coupling and Cross Section for the e + e − → h h f f ¯ $e^{+} e^{-} \rightarrow hhf\overline {f}$ (f≠t) in Type-I 2HDM

International Journal of Theoretical Physics - The objective of this study is to correlate the scaling factor of the Standard Model (SM) like Higgs boson and the cross section ratio of the process...     

Barrier height enhancement of metal/semiconductor contact by an enzyme biofilm interlayer

A metal/interlayer/semiconductor (Al/enzyme/p-Si) MIS device was fabricated using α-amylase enzyme as a thin biofilm interlayer. It was observed that the device showed an excellent rectifying behavior and the barrier height value of 0.78?eV for Al/α-amylase/p-Si was meaningfully larger than the one of 0.58?eV for conventional Al/p-Si metal/semiconductor (MS) contact. Enhancement of the interfacial potential barrier of Al/p-Si MS diode was realized using enzyme interlayer by influencing the space charge region of Si semiconductor. The electrical properties of the structure were executed by the help of current–voltage and capacitance–voltage measurements. The photovoltaic properties of the structure were executed under a solar simulator with AM1.5 global filter between 40 and 100?mW/cm² illumination conditions. It was also reported that the α-amylase enzyme produced from Bacillus licheniformis had a 3.65?eV band gap value obtained from optical method.     

Selectivity in the aggregates of the chiral organolithium N-Boc-2-lithiopiperidine with a chiral ligand: a DFT study

In this paper the aggregates of the chiral organolithium N-Boc-2-lithiopiperidine [Boc=CO₂C(CH₃)₃], which play an important role in the formation of chiral 2-substituted piperidines found in many alkaloid structures and medicinal compounds, have been investigated within the framework of Density Functional Theory (DFT) calculations. In the complex structures, the lithium atoms are tetra-coordinated, the diaminoalkoxide ligand is tridentate to one lithium atom and forms a chelate with the substrate which is stabilized by the solvent diethyl ether. The same type of bonding was observed for all the different ligand-bound structures; for ligands 6 and 7, which have bulky substituents, selectivity was in agreement with experiment. The results shed light on the microscopic structures of these species and suggest a potential ligand, 11, to yield high enantioselectivity.     

Synthesis of benzoic acids and polybenzamides containing tertiary alkylamino functionality

The high-yielding and easily scalable synthesis of a number of benzoic acids bearing a tertiary alkylamino functionality has been achieved. The flexible synthesis began from readily available aminobenzoic acids or terephthaloyl chloride and requires almost no chromatography. Coupling of the synthesised amino acids to a range of substituted anilines was achieved when utilizing a specific combination of DIC, HOBt and DMAP.     

Dynamics and control of a system of two non‐interacting preys with common predator

In this paper, we consider a Holling type model, which describes the interaction between two preys with a common predator. First, we give some sufficient conditions for the globally asymptotic stability and prove that local stability implies global stability. Then, we present a set of sufficient conditions for the existence of a positive periodic solution with strictly positive components. Finally, the optimal control strategy is developed to minimize the number of predator and maximize the number of preys. We also show the existence of an optimal control for the optimal control problem and derive the optimality system. The technical tool used to determine the optimal strategy is the Pontryagin Maximum Principle. Finally, the numerical simulations of global stability and the optimal problem are given as the conclusion of this paper. Copyright © 2011 John Wiley & Sons, Ltd.