Kinetic Analysis of Multi Enzyme Systems: A Case Study of the Closed System of Creatine Kinase, Hexokinase and Glucose 6-Phosphate Dehydrogenase

This paper describes a general methodology to handle closed multi enzyme systems using mixture of symbolic (which depends on the Gröbner Basis technique) and numerical computation methods. The applicability of the proposed method has been examined for the closed three-enzyme system of rabbit heart creatine kinase (EC 2.7.3.2), yeast hexokinase (EC 2.7.1.1) and human erythrocyte glucose 6-phosphate dehydrogenase (EC 1.1.1.49) using experimental data.     

A simple theory of 40 K superconductivity in MgB2: first-principles calculations of Tc, its dependence on boron mass and pressure

We have studied the superconducting properties of MgB₂ from first-principles under isotropic, uniaxial, and biaxial compressions. We find that the in-plane boron phonons near the zone-center are very anharmonic and strongly coupled to the planar B σ bands near the Fermi level. This mode is found to be the key to quantitatively explain the observed high T_c, the total isotope effect and the pressure dependence of T_c. We propose that a stringent test on the hole and phonon based theories of the superconductivity in MgB₂ would be a measurement of the biaxial ab-compression dependence of T_c.     

Biological distribution of iodo-allyl gabapentin and iodo-gabapentin

Gabapentin (GBP) is an anticonvulsant and is widely used in the treatment of epilepsy. In this study, GBP and an allyl derivative of GBP were radioiodinated with ¹³¹I using the iodogen method; then their radiopharmaceutical potential in rats and rabbits was investigated. The radiochemical purity of ¹³¹I-GBP and its derivatives was determined by RTLC. The labeling yield was 95±2%. Biological evaluation was performed in normal rats and rabbits. Labeled compounds were intravenously injected into two rabbits via the ear vein after anesthetizing. The dynamic and static scintigrams were obtained using a gamma camera at different time. Then the labeled compounds were administered intravenously into the rats. The distribution was studied by counting the radioactivity in the removed organs. The results of biodistribution in the rats showed the clearance of ¹³¹I-ALGBP was faster than ¹³¹I-GBP. On the other hand, the uptake of ¹³¹I-ALGBP in the brain was higher than ¹³¹I-GBP at 60 minutes.     

Synthesis of Some Novel Norbornene‐Fused Pyridazines as Potent Inhibitors of Carbonic Anhydrase and Acetylcholinesterase

The reaction of benzocyclic norbornene derivatives with tetrazines provided the 1,3‐dihydropyridazine derivatives as a single product. The dihydropyridazine derivatives have been dehydrogenated with phenyliodine bis(trifluoroacetate) to yield the corresponding pyridazines in a high yield. Two stable diazines, primary product of corresponding 1,4‐dihydropyridazine, were also isolated. Structures were then determined by ¹H‐NMR, and ¹³C‐NMR beside to elemental analyses. The novel pyridazine derivatives ( 8 , 9 ) efficiently inhibited the cytosolic human carbonic anhydrase isoenzymes I and II (hCA I and II). In addition, these novel pyridazine derivatives ( 8 , 9 ) were evaluated for their in vitro acetylcholinesterase inhibitory activity. Ligand–receptor interactions are tested using molecular docking simulations. Obtained docking scores are in good agreement with in vitro results.     

Preparation of novel pyrrol-2-one derivatives via an effective synthesis of new oxazole scaffold

A convenient procedure for the preparation of oxazole and pyrrole derivatives is described. 2-Amino-1,3-oxazol-2-ones 3a,b were first synthesized from the cyclocondensation reactions of cyanamide (2) with 4-ethoxycarbonyl-5-aryl-2,3-furandione 1a,b, and then new pyrrol-2-ones 5 were synthesized from the reaction of the compounds 3 with various aromatic amines 4.     

Stacking effects on local structure in RNA: changes in the structure of tandem GA pairs when flanking GC pairs are replaced by isoG-isoC pairs

The Watson-Crick-like isoG-isoC (iGiC) pair, with the amino and carbonyl groups transposed relative to the Watson-Crick GC pair, provides an expanded alphabet for understanding interactions that shape nucleic acid structure. Here, thermodynamic stabilities of tandem GA pairs flanked by iGiC pairs are reported along with the NMR structures of the RNA self-complementary duplexes (GCiGGAiCGCA)2 and (GGiCGAiGCCA)2. A sheared GA pairing forms in (GCiGGAiCGCA)2, and an imino GA pairing forms in (GGiCGAiGCCA)2. The structures contrast with the formation of tandem imino and sheared GA pairs flanked by GC pairs in the RNA self-complementary duplexes (GCGGACGC)2 and (GGCGAGCC)2, respectively. In both iGiC duplexes, Watson-Crick-like hydrogen bonds are formed between iG and iC, and iGiC substitutions result in less favorable loop stability. The results provide benchmarks for testing computations of molecular interactions that shape RNA three-dimensional structure.     

Higher order approximate periodic solutions for nonlinear oscillators with the Hamiltonian approach

In this work, the Hamiltonian approach is applied to obtain the natural frequency of the Duffing oscillator, the nonlinear oscillator with discontinuity and the quintic nonlinear oscillator. The Hamiltonian approach is then extended to the second and third orders to find more precise results. The accuracy of the results obtained is examined through time histories and error analyses for different values for the initial conditions. Excellent agreement of the approximate frequencies and the exact solution is demonstrated. It is shown that this method is powerful and accurate for solving nonlinear conservative oscillatory systems.     

Density functional theory study on the identification of 3-[(2-morpholinoethylimino)methyl]benzene-1,2-diol

This study deals with the identification of a title compound, 3-[(2-morpholinoethylimino)methyl]benzene-1,2-diol by means of quantum chemical calculations. The optimized molecular structures, vibrational frequencies and corresponding vibrational assignments, thermodynamic properties, charge analyses, nuclear magnetic resonance (NMR) chemical shifts and ultraviolet-visible (UV-vis) spectra of the title molecule in the ground state were evaluated using density functional theory (DFT) with the standard B3LYP/6-311++G(d,p) method and basis set combination for the first time. Theoretical vibrational spectra of the title compound were interpreted with the aid of normal coordinate analysis based on scaled density functional force field. The results show that the obtained optimized geometric parameters (bond lengths, bond angles and bond dihedrals) and vibrational frequencies were observed to be in good agreement with the available experimental results. Moreover, the calculations of the electronic spectra, (13)C and (1)H chemical shifts were compared with the experimental ones. Furthermore, we not only simulated the frontier molecular orbitals (FMO) and molecular electrostatic potential (MEP) but also determined the transition states and energy band gaps, as well. It was found that charge analyses supported the evidences of MEP. Infrared intensities and Raman activities were also reported.     

Topological Soliton and Other Exact Solutions to KdV–Caudrey–Dodd–Gibbon Equation

This paper studies the KdV–Caudrey–Dodd–Gibbon equation. The modified F-expansion method, exp-function method as well as the G′/G method are used to extract a few exact solutions to this equation. Later, the ansatz method is used to obtain the topological 1-soliton solution to this equation. The constraint conditions are also obtained that must remain valid for the existence of these solutions.