Water-miscible organic solvent

In reversed-pViase chromatography (RPC), the mobile phase modulator is typically a water-miscible organic solvent, and the stationary phase is a hydrophobic adsorbent. In this case, the logarithm of solute retention factor is commonly found to be linearly related to the volume fraction of the organic solvent. 

If the column is contaminated with hydrophobic compounds, clean it with water-miscible organic solvents such as MeOH, CHjCN, or EtOH. Concentrations of 10-20% organic in water should be sufficient for cleaning. 

As described above, the enzymatic polymerization of phenols was often carried out in a mixture of a water-miscible organic solvent and a buffer. By adding 2,6-di-0-methyl-(3-cyclodextrin (DM-(3-CD), the enzymatic polymerization of water-insoluble m-substituted phenols proceeded in buffer. The water-soluble complex of the monomer and DM-(3-CD was formed and was polymerized by HRP to give a soluble polymer. In the case of phenol, the polymerization took place in the presence of 2,6-di-O-methyl-a-cyclodextrin (DM-a-CD) in a buffer. Only a catalytic amount of DM-a-CD was necessary to induce the polymerization efficiently. Coniferyl alcohol was oxidatively polymerized in the presence of a-CD in an aqueous solution. ... 

Tissue samples are homogenized in the presence of a water miscible organic solvent to promote efficient extraction. 

The isocratic reversed phase solvent system consists of water (polarity, p = 10.2), the most polar solvent in RPLC, as a primary solvent to which water-miscible organic solvents such as methanol (p = 5.1), acetonitrile (p = 5.8), or tetrahydrofuran (p = 4.0) are added. In order to optimize the speed of separation for an analyte pair, the proportions of water to nonpolar solvent are chosen such that the capacity factor of the last-eluting analyte of interest has a value of about 2.13... 

Mathieu, S., F. Bigey et al. (2007). Production of a recombinant carotenoid cleavage dioxygenase from grape and enzyme assay in water-miscible organic solvents. Biotechnol. Lett. 29(5) 837-841. 

Vazquez-Duhalt, R. Semple, K. M. Westlake, D. W. S., and Fedorak, P. M., Effect of Water-Miscible Organic-Solvents on the Catalytic Activity of Cytochrome-C. Enzyme and Microbial Technology, 1993. 15(11) pp. 936-943. 

Torres, E. Tinoco, R., and VazquezDuhalt, R., Solvent Hydrophobicity Predicts Biocatalytic Behaviour of Lignin Peroxidase and Cytochrome C in Aqueous Solution of Water-Miscible Organic Solvents. Journal of Biotechnology, 1996. 49(1-3) pp. 59-67. 

Dissolve the bis-NHS-PEG compound in a dry, water-miscible organic solvent to make a concentrated stock solution. To prepare a lOmM solution of the bis-NHS-PEG9 reagent, dissolve 7mg/ml of DMAC for the bis-NHS-PEG5 reagent dissolve 5.3mg/ml of DMAC. 

The NHS ester compounds are sensitive to hydrolysis in aqueous solution, and they likely will hydrolyze faster than more hydrophobic biotinylation compounds due to their hydrophilic-ity. If a stock solution is made at a higher concentration to facilitate the addition of a small amount to a reaction solution, the initial solution should be made in a water-miscible organic solvent that is dried with a molecular sieve. Suitable solvents include DMAC, DMSO, or DMF. If using DMF, use only highly pure solvent, as it may contain amines that can react with the NHS ester groups (Figure 18.13). 

T. Montensinos, S.P. Munguia, F. Valdez, and J.L. Marty, Disposable cholinesterase biosensor for the detection of pesticides in water-miscible organic solvents. Anal. Chim. Acta 431, 231-237 (2001). 

The investigation of enzymes in water-miscible organic solvents trivially called non-aqueous enzymology about 20 years ago became an independent part of modem biochemistry and enzymology [174-176], In concentrated organic solvents, with the water content less than 10-15%, the enzymes are rather stable and can even retain their activity [176, 177], Recent studies even demonstrated improvement of the enzyme activity in concentrated organic solvents [178],... 

The structural integrity of enzymes in aqueous solution is often compromised by the addition of small quantities of water-miscible organic solvents. However, there are numerous examples, particularly using extremophiles, where enzymes have been successfully employed in organic solvent-aqueous mixtures.A good example is the savinase-catalysed kinetic resolution of an activated racemic lactam precursor to abacavir in 1 1 THF/water (Scheme 1.39). The organic solvent is beneficial as it retards the rate of the unselective background hydrolysis. 

The use of water-miscible organic solvent-water mixtures is a particularly attractive method for use with cofactor-dependent enzymes due to its simphcity. The high water content can allow dissolution of both enzyme and cofactor, whilst the water-miscible solvent can provide a dual role in both substrate dissolution and as a cosubstrate for cofactor recycling (substrate-coupled cofactor recycling).The asymmetric reduction of a ketone intermediate of montelukast using an engineered ADH in the presence of 50 % v/v isopropanol offers a powerful demonstration of this methodology (Scheme 1.55). 

On addition of a small volume of the strong acid or strong base to a solution of the weak base or weak acid, the pH rises or falls rapidly to about 1 pH unit below or above the p Ta value of the acid or base. Often a water miscible organic solvent such as ethanol is used to dissolve the analyte prior to addition of the aqueous titrant. 

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