Buffer organic solvent

In order to select a carrier solution composition which would provide an overall maximum response for MS detection, two modifiers were selected, acetonitrile and methanol, and two buffers, i.e. ammonium acetate (10 mmol pH 7.5) and ammonium formate (10 mmol L pH 7.5). Biotin and fluorescein-biotin were dissolved in various binding buffer-organic solvent mixtures ranging from 90 10 (v/v) to 50 50 (v/v) at two concentration levels (0.01 ng 1 ng pL ) and 20 pL were injected and analyzed by MS in full-scan and SIM mode. The maximum response was found with 50% methanol, which was about a factor 2x higher than for 10% methanol. Since the proteins can denaturate or protein-ligand complexes can dissociate at relatively low percentages of organic modifier in further experiments only 10% methanol is used in the carrier solution. 

One method is to run the reaction in an aqueous buffer/organic solvent biphasic system. This makes it possible to work at high substrate and product concentrations and at the pH-optimum of the enzyme. In addition, in water-immiscible solvents the non-enzymahc addition of HCN to the carbonyl group is non-existent or extremely slow. Possible disadvantages are enzyme deactivation at the interface and the presence of organic solvent dissolved in the aqueous phase [15, 17, 18]. 

In addition, Giacomini et al. have shown that the asymmetric synthesis of (25)-2-phenylpropanol and (25)-2-(4- o-butylphenyl)propanol ((5)-ibuprofenol) could be achieved by means of horse liver alcohol dehydrogenase (HLADH) in buffered aqueous solution or buffered organic solvent mixtures. Indeed, the reduction through DKR of the corresponding aldehydes occurred with both excellent yields and enantioselectivities, as shown in Scheme 3.13. The value of these results resided in the appKcation of these two chiral alcohols as intermediates for the synthesis of optically active pharmaceutical products of the profen class (ibuprofen) and fragrances. 

ChemoenzymatiC Synthesis. Original oligosaccharides bifunctional-ized with fluorescent entities were synthetized in the presence of a mutant of Humicola insolens endoglucanase (318). Hemithiocellodextrins with degree of polymerization from 4 to 14 were synthetized in the presence of a cellulase in buffer/organic solvent (319). 

Anthocyanins (Flavanones enantiomers) Black currant Buffer/organic solvent DAD D... 

Flavonols Rosemary honey Buffer/organic solvent ESl-MS z... 

Lipoxygenase (EC 1.13.11.12) catalyzes the dioxygenation of polyunsaturated fatty acids to form their corresponding hydroperoxides. Reduc derivatives of these have the potential to replace ricinoleic acid in industrial products. Currently ricinoleic acid is obtained from castor oil, a commodity that is imported into the U.S. at the level of thirty thousand metric tons per year (1). A method for immobilizing lipoxygenase was developed, and the use of this immobilized preparation to produce die hydroperoxide of linoleic acid (HPOD) in aqueous buffer-organic solvent mixtures was investiga. ... 

Eluents for lEC are usually aqueous, salt-buffered solutions, and the separation process for the species of interest is mainly controlled by a change in the concentration and/or the nature of the buffer. Organic solvents such as methanol are often added to the mobile phase for control of the selectivity or to change solvent strength, retention times or column efficiency. 

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