Cosolvents definition

While it is tempting to explain regulatory and cosolvent effects on the basis of conformational changes favorable or unfavorable to enzyme activity, it is much more difficult to demonstrate the actual involvement, amount, and structural details of such changes. Experimental evidence consists in most cases of bits and pieces provided by techniques such as absorption and fluorescence spectroscopy, circular dichroism, and magnetic circular dichroism. These tools work in solution (and, when desired, at subzero temperatures) to investigate not simply empty enzymes but enzyme—substrate intermediates. However, even with this information, the conformational basis of enzyme activity remains more postulated than demonstrated at the ball and stick level, and in spite of data about the number and sequence of intermediates, definition of their approximate nature, rate constants, and identification of the types of catalysis involved, full explanation of any particular reaction cannot be given and rests on speculative hypothesis. 

Based on the previous considerations, some authors proposed thermodynamic-based approaches to SAS. De la Fuente Badilla et al attempted to develop a thermodynamic-based criterion for optimum batch antisolvent precipitation (GAS) using a definition of the volume expansion that takes into account the molar volume of the system studied. They analyzed various binary and ternary systems and concluded that the pressure corresponding to a minimum value of the liquid-phase volume expansion coincides with the pressure at which the solute precipitates. In a subsequent work, Shariati and Peters further highlighted the role of SC-CO2 in GAS. It acts as a co-solvent (cosolvency effect) at lower concentrations, whereas at higher concentrations it acts as an antisolvent. 

Experimental data suggest that the optimum salinity varies linearly with the cosolvent concentration. Therefore, p7 can be estimated from the slope of the straight line of normalized optimnm salinity (C5i,op/C i,op) versns f in the case without divalent cations, as schematically shown in Figure 7.20. To obtain the effect of cosolvent on the shift in optimum salinity, P, we need to measure the volume fraction diagram for at least two different cosolvent concentrations and must know C i op. According to the definition, ff is defined as V7/(V7 + V3). 

CAS 91744-63-7 EINECS/ELINCS 294-627-9 Synonyms Glycerides, palm kernel oil mono-, di-, and tri-, acetates Definition Acetyl ester of palm kernel glycerides Uses Lubricant and plasticizer for plastics and coatings emollient, emulsifier in cosmetics food-grade plasticizer for PVC cosolvent for polar additives in low polarity systems food additive... 

CAS 10233-13-3 EINECS/ELINCS 233-560-1 Synonyms Dodecanoic acid, 1-methylethyl ester 1-Methylethyl dodecanoate Definition Ester of isopropyl alcohol and lauric acid Empirical C15H30O2 Formula CH3(CH2)ioCOOCH(CH3)2 Toxicology TSCA listed Uses Emollient, lubricant, plasticizer, and cosolvent in cosmetics and pharmaceuticals defoamer in food-contact paper/paperboard in food-contact textiles... 

CAS 42131-28-2 EINECS/ELINCS 255-674-0 Synonyms 2-Hydroxypropanoic acid, isostearyl ester Isooctadecyl 2-hydroxypropanoate Definition Ester of isostearyl alcohol and lactic acid Empiricai C21H42O3 Formuia CH3CHOHCOOC18H37 Uses Emollient, substantivity agent, softener, slip agent, lubricant, cosolvent, solubilizer in cosmetics and pharmaceuticals Manuf./Distrib. ASiE Connock http //www. connock. co. uk Trade Name Synonyms Patlac IL [Am. Ingreds. http //www. americaningredients. com, R. I. T.A. http //www.ritacorp.com], Pelemol ISL [Phoenix http //www.phoenix-chem.com] Isostearyl myristate CAS 72576-81-9... 

Definition PEG ether of lanolin alcohol with avg. ethoxylation value of 5 Properties H LB 7.7 nonionic Toxicology TSCA listed Uses Emulsifier, emollient, stabilizer, solubilizer, cosolvent, wetting agent, dispersant, conditioner, vise, control agent for cosmetics, pharmaceuticals, creams and lotions bromo dye solvent Trade Name Synonyms Aqualose W5 [CrodaAA/estbrook] Fancol LA-5 t[Fanning... 

Definition Methyl ester of cottonseed oil Uses Solvent, cosolvent, penetrant in industrial, food processing, and agric. applies. in textile processing aids in printing inks Trade Name Synonyms Norfox MCS [Norman, Fox http //www.norfoxx.com]... 

Definition Mixt. of fatty alcohols derived from tallow Formula CH3(CH2)nOH, n = 16, 18 Properties Waxy solid m.p. 46 C Uses Emollient, emulsifier, consistency agent, cosolvent for cosmetics, skin creams/lotions defoamer in paper/paperboard in contact with aq./fatty foods... 

Two measured solubilities will define the value of o that is specific to a sol-ute/cosolvent pair. The value of a is also dependent of the solubility unit selected and on whether 10-based or e-based logarithm is used. The magnitude of o reflects the difference in molecular interactions between solute/cosolvent and solute/water. When applied to describe cosolvency, a is like a microscopic partition coefficient if water and cosolvent are thought of as two independent entities. There had been other definitions of a, such as the... 

The focus of our discussion so far has been the following how do cosolvent molecnles modulate biochanical reactions Any biochemical reaction, by definition, involves more than two states—such as free and bound states, or nnfolded and folded states. This chapter so far has focused upon the differences in solute-solvent interactions... 

Experimental measurements of solubility are influenced by many different factors, including the purity of the solute and solvent, presence of cosolvents, presence of salts, temperature, physical form of the undissolved solute, ionization state, and solution pH [18]. Consequently many different definitions of solubility are in common use in the published literature. Here we discuss the intrinsic aqueous solubility, Sg, which is defined as the concentration of the neutral form of the molecule in saturated aqueous solution at thermodynamic equilibrium at a given tanperature [18-20]. Intrinsic aqueous solubility is used to calculate dissolution rate and pH-dependent solubility in models such as the Noyes-Whimey equation [21] and the Henderson-Hasselbalch equation [22, 23], respectively. Prediction of the intrinsic aqueous solubility of bioactive molecules is of great importance in the biochemical sciences because it is a key determinant in the bioavailability of novel pharmaceuticals [1, 3, 24-26] and the environmental fate of potential pollutants [27, 28],... 

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