Glycerol, enzymatic analysis

Wu LC, Cheng CM (2005) Flow-injection enzymatic analysis for glycerol and triacylglycerol. Anal Biochem 346 234-240... 

Traditional methods of analysis for determination of principal organic acids, glycerol and sugars in wine are based on enzymatic or colorimetric reactions ethanol is determined by distillation of wine and density measurement of the distillate. In Table 1.2, data of organic acids, glycerol, glucose, fructose and ethanol determined by HPFC are reported as a percentage of results obtained by the traditional methods. 

Fig. 7.7 Analysis of Aventis inhibitor 7500 using the cellular lipolysis assay Isolated rat adipocytes were incubated with NBD-labeled dodecanoic acid (for incorporation into neutral lipid droplets) and then challenged with 1 pM isoproterenol (to stimulate lipolysis) prior to addition of increasing concentrations of inhibitor 7500. After incubation (1 h at 37°C), the adipocytes were separated from the medium by flotation through an oil layer. Portions of the medium were enzymatically analyzed for glycerol. Portions of the perchloric acid extracts from the adipocytes were analyzed in duplicate by thin-layer chromato-...

Many characteristics of a protein in aqueous solvents are connected to its preferential solvation (or preferential hydration). The protein stability is a well-known example. Indeed, the addition of certain compounds (such as urea) can cause protein denatur-ation, whereas the addition of other cosolvents, such as glycerol, sucrose, and so forth, can stabilize at high concentrations the protein structure and preserve its enzymatic activity (Kuntz Jr. and Kauzmann 1974 Timasheff 1992, 1993, 1998a). Analysis of literature data danonstrates that as a rule T > 0 for the former and < 0 for the latter compounds. Recently, we showed how the excess (or deficit) number of water (or cosolvent) molecules in the vicinity of a protein molecule can be calculated in terms of T2 , the molar volume of the protein at infinite dilution, and the properties of the protein-free mixed solvent (Shulgin and Ruckenstein 2005a). The protein solubility in an aqueous mixed solvent is another important quantity which can be connected to the preferential solvation (or hydration) (Arakawa and Timasheff 1984, 1985b, 1987 Timasheff and Arakawa 1988 Arakawa, Bhat, and Timasheff 1990) and can help to... 

In the field of wine analysis within the European Union, the analytical methods are defined to a large extent by VO (EWG) No. 2676/90 [216]. Therefore, wet-chemical and enzymatic techniques still play an important role. However, the hquid chromatographic determination of the main sugars such as glucose, fructose, and sucrose together with glycerol and ethanol gains in importance due to its potential for automation. Separation is performed on a calcium-loaded ion-exclusion phase with pure de-ionized water as an eluant refrachve index detection is applied [217]. Thus, carbohydrate separation is based on the formation of different coordination complexes with metal cations, whose stability de-... 

Incubations were performed in duplicate in each experiment. All statistical evaluations were based on paired comparisons. FFA were evaluated by the procedure of Dole and Meinertz and glycerol by the enzymatic method of Wieland (3, 4). The triglycerides content of the flasks, based on analysis of the free fatty acids after saponification was used for quantitative evaluation of the cells, present in each flask. 

Independently of whether chemical or enzymatic methods are used for synthesis, the STAG produced have to be analysed carefully. Besides the total fatty acid composition and the content of partial glycerol esters and free fatty acids, a regiospecific analysis of the fatty acid distribution is of utmost importance. In addition, sophisticated analytical methods are required to optimize a specific reaction and to measure changes in the sTAG composition during synthesis. 

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