Purification and Partial Characterization of (6-4) Photoproduct DNA Photolyase from Xenopus laevis

Abstract— The (6-4) photoproduct DNA photolyase was detected in two vertebrate animals Crotalus atrox (rattlesnake) and Xenopus laevis (South African clawed toad). The enzyme was extensively purified from X. laevis and characterized. The highly purified enzyme is fluorescent with an excitation maximum at 420-440 nm and emission maximum at 460-480 nm. The photorepair action spectrum matches the fluoresoence excitation spectrum with a 430 nm maximum.     

Ascorbic acid as a new reductant in the thiocyanate method for the spectrophotometric determination of rhenium

Summary A spectrophotometric determination of rhenium is based on its reduction with ascorbic acid in the presence of thiocyanate. The orange-yellow complex is extracted into isoamyl alcohol and the absorbance measured at 430 nm. Various foreign ions do not interfere. Molar absorptivity and Sandell's sensitivity are 31162.79 l/mol/cm and 0.0059 g/cm², respectively.     

Enantioseparation of (RS)-Bupropion and determination of configuration

Racemate of (RS)-Bupropion (Bup) has been separated by derivatization approach and thin layer chromatography (TLC). It was extracted from commercially available tablets, purified, and characterized. A new chiral derivatization reagent (CDR) was synthesized by introducing L-leucine amide and butoxy group in cyanuric chloride (CC) moiety. Derivatization reaction was carried out using a two-fold molar excess of CDR under microwave irradiation (MWI). The diastereomeric pair was separated by TLC and the same were recovered by the preparative method; these were purified and characterized. Absolute configuration of the Bup moiety in the diastereomeric derivatives was confirmed by recording their ¹HNMR spectra and thus elution order was also established.     

NMR study of poly-p-isopropyl-α-methylstyrene

220 MHz NMR spectra of sample of poly-p-isopropyl-α-methylstyrene prepared through anionic (A) and cationic (B) polymerizations are studied. Peaks at τ values of 9.07, 9.41, and 9.71 are assigned to isotactic (i), heterotactic (h), and syndiotactic (s) α-methyl triads, respectively. From the α-methyl triads and the β-proton tetrads it is found that polymer A deviates little from Bernoullian statistics and that first-order Markov configurational statistics applies to polymer B. Isopropyl methine and methyl proton resonances are also analyzed in terms of the configurational statistics of the polymer. Resonances of the phenyl protons are assigned with increasing field to s, h, i meta and ortho protons.     

Immobilization and Characterization of Lactate Dehydrogenase on TEOS Derived Sol-Gel Films

Physical adsorption and physical entrapment techniques have been utilized for the immobilization of lactate dehydrogenase (LDH) on tetraethylorthosilicate (TEOS) derived sol-gel films. The enzyme (LDH) activity has been assayed as a function of time, temperature, pH and pyruvate concentration. The results of photometric measurements used for monitoring the reaction yield a response time of about 1 min, linearity over a concentration range of 0–1.5 × 10^-3 M and detection limit of 5 × 10^-5 M. The TEOS sol-gel films containing LDH have been found to be stable for about 30 days at temperatures 4 to 10°C.     

Spectrographic analysis of boron nitride for trace impurities

A d.c. arc emission spectrographic method has been developed for the determination of nine trace impurities in boron nitride. The charge for exciting the sample contains equal quantities of boron nitride and graphite (containing 2% NaF as carrier and 1% La(2)O(3) as an internal standard). The method is useful in the determination of impurities in the range 2-1000 ppm, with a mean relative standard deviation of 13%.     

Intradiffusion and viscosity measurements in acidified iron(III) chloride solutions at 25°C

Intradiffusion of species in acidified (using eithe hydrochloric or perchloric acid) iron(III) chloride solutions has been studied using labeled iron(III), chloride and water. Comparison with data for iron(III) perchlorate has enabled the influence of complexed species upon the diffusion to be ascertained. The chloro-iron species formed have larger diffusion coefficients than the free iron(III) ion as would be expected from their lower net charge. Simple diffusion models have been employed to enable estimates of the diffusion of the complexed species and of the free chloride diffusion coefficients to be obtained. These are discussed in relation to literature data for similar systems. In addition esitmates of the effective hydration of the iron(III) species in solutions have been obtained from the diffusion data. These are discussed in relation to two other trivalent metal salt systems, chromium chloride and lanthanum chloride; the overall hydration of the three cations is virtually identical.     

Assignment of 13C resonances of a nematic liquid crystal using off-magic angle spinning

A novel method for assigning the resonances in the 13C NMR spectrum of a static liquid crystalline sample in its nematic phase is proposed. The method is based on the fact that the carbon chemical shifts in the isotropic phase and in the oriented phase under static and off-magic angle spinning (OMAS) conditions are uniquely related by the tensorial property of the CSA tensor, requiring just one OMAS spectrum and the assignment in the isotropic phase. A computational procedure is proposed to take into account deviations arising out of non-ideal experimental conditions and the assignments are made by identifying the minimum in the differences in the frequencies between calculated and experimental line positions. Practical implementation of the method has also been demonstrated in the case of the liquid crystal N-(4-ethoxybenzylidene)-4-n-butylaniline.