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The interaction between an aqueous phthalate buffer and the rare earth metal europium(III) was investigated to demonstrate the effect of buffer complexation of Eu on solvent extraction slope analys...

In this paper, we describe the apparent production of enzymatically synthesized amylose in DMSO by means of the calcium alginate hydrogel beads/DMSO system as the reaction field of the phosphorylase-catalyzed enzymatic polymerization. When the calcium alginate hydrogel beads including glucose-1-phosphate, maltoheptaose, and phosphorylase were suspended in DMSO and the system was slowly stirred at 40°C for 12 h, the reaction proceeded to produce amylose, which eluted to the DMSO solution. The obtained amylose was purified by the treatment with ion-exchange resins, and its structure was confirmed by the 1H NMR spectrum. The time-course experiment in the present system revealed that the phosphorylase-catalyzed enzymatic polymerization was carried out for 15 min on the inside of the calcium alginate hydrogel beads and the produced amylose was gradually eluted to the surrounding DMSO solution. The comparison of the present system with the general enzymatic polymerization in aqueous buffer solution suggested th...

The key to obtaining optimum performance of an enzyme is often a question of devising an effective method for its immobilization. This review describes a novel, versatile and effective methodology for enzyme immobilization, namely, as cross-linked enzyme aggregates (CLEAs). The method is exquisitely simple – involving precipitation of the enzyme from aqueous buffer followed by cross-linking of the resulting physical aggregates of enzyme molecules – and amenable to rapid optimization. It is applicable to a wide variety of enzymes, including cofactor-dependent oxidoreductases and lyases, and affords stable, recyclable catalysts with high retention of activity, sometimes higher than that of the free enzyme it was derived from. The enzyme does not need to be of high purity. Indeed, the methodology is essentially a combination of purification and immobilization in one step. The technique is also applicable to the preparation of combi-CLEAs, containing two or more enzymes, for use in one-pot, multi-step synthes...

The force of adhesion between crossed carbon filaments submerged in an aqueous buffer solution has been measured. The decrease of this force, observed on addition of surfactants (cetyltrimethyl ammonium bromide or decylsulphonic acid) to the solution, is in agreement with that predicted by the thermodynamic theory of adhesion (B. V. Deryagin, Koll. Z. 69, 155 (1934)). A relation between the force of adhesion between the filaments and their wetting properties was derived and is supported by the experiments. It is concluded that adhesion in the above systems can be described by thermodynamics.

The electroreduction of dimethylarsenic acid (cacodylic acid), (CH3)AsO2H, and methylarsonic acid, (CH3)ASO3H2, in both nonaqueous and aqueous buffer electrolytes, is described.

A simple reverse-phase high performance liquid chromatographic method is evaluated for the estimation of octanol-water partition coefficients (log P) of organic compounds by correlation with their chromatographic capacity factors (k′). Using an unmodified commercial octadecylsilane column and a mobile phase consisting of methanol and an aqueous buffer, a linear relationship is established between the literature log P values of 68 compounds and the logarithms of their k′ values. For the determination of the partition coefficients of unknowns, one of two sets of standards is used to calibrate the system, the choice being dependent on the hydrogen-bonding character of the compounds being evaluated. The overall method is shown to be rapid and widely adaptable and to give log P data which are comparable to results obtained by classical or other correlation methods.

Rhodamine-123, a mitochondrial-specific dye, is currently of interest as a potential anticarcinoma agent. We now report an analytical method suitable for monitoring this agent in a variety of biological matrices. The drug is easily extractable into organic solvent in high yield (>90%). Analysis is conducted by reversed-phase HPLC using a phenyl column and an organic/aqueous buffer mobile phase, with signal detection by flow fluorometry. The assay shows linearity over the concentration range of 5-4000 ng/ml, with a limit of sensitivity of 100 pg. Preliminary animal data confirms the suitability of the assay for detailed drug metabolism and dispositional studies.

Equilibrating cylindrical isoelectrofocusing gels in 55% methanol rather than in aqueous buffer before starting the SDS dimension substantially increased the resolution obtained on 2-D gels. This effect may result from the in situ precipitation of focused proteins eliminating band diffusion prior to the second dimension.

Ap(NH2)dT was synthesized as a model compound for a study of the stability of the phosphodiester-amide interribonucleotide linkage in neutral aqueous solution, by photolyzing AnBnp(NH2)dT in anhydrous p-dioxane. Ap(NH2)dT proved to be unstable even under anhydrous conditions and could not be isolated. It was rapidly decomposed in neutral aqueous buffer solution, at 25°C, to give A>p, dT and ApdT. Three unstable intermediates of this decomposition, A>pNH2, ApNH2 and A>pdT were detected by 31P NMR. On the basis of the structure of the products, a mechanism is proposed for the decomposition.