Enzymatic methods determined using

Chillproofers are added to freshly brewed beers to prevent the formation of haze upon cold storage. Papain-based enzymes have been used as chillproofers and their addition have to be monitored carefully, as overdosage results in flat beer. According to Skerritt et al (146), enzymatic methods currently used lack sensitivity or are slow and tedious. They have developed a polyclonal antibody-based kit for determination of these chillproofers. 

HPLC and enzymatic methods are used for the determination of citric and malic acids in routine analysis. Tartaric, fumaric, and phosphoric acids are normally determined by HPLC. The choice of a given HPLC method depends on the nature of acids and sample matrix. The most general method is ion-exclusion chromatography followed by RP chromatography because these two methods provide betteq faster, and more reliable data compared to ion-exchange and ion-pair RPLC. The better-shape peaks are obtained employing ion-exclusion... 

ADH does not react with methanol or acetone but reacts to a lesser degree with n-propanol, isopropanol, and n-butanol. EMIT is free of interference from small molecular weight alcohols, aldehydes, ketones, and glycols. Automated enzymatic methods are useful for clinical purpose because a large number of samples can be handled in a short time period. In the forensic laboratory, however, chemical methods for determining ethanol in biological samples are not generally used because they are not specific. 

Alizade and Simon (1973) studied the stereochemistry of this transformation. Enzymatic methods were used to determine the specific quantities of the stereoisomers. In addition, the fermentation of radioactively labeled glucose and malic acid permitted the study of their products. The heterofermentative cocci (Oenococcus), abundant or exclusive during winemaking, were found to present several properties. They form exclusively D-lactic acid from glucose (Chapter 4) and exclusively L-lactic acid from L-malic acid (Figure 5.4). 

Determination of DNA Sequence Information. Almost all DNA sequence is determined by enzymatic methods (12) which exploit the properties of the enzyme DNA polymerase. Whereas a chemical method for DNA sequencing exists, its use has been supplanted for the most part in the initial deterrnination of a sequence. Chemical or Maxam-Gilbett sequencing (13) is mote often used for mapping functional sites on DNA fragments of known sequence. 

Molecular weight of the components of the enzymatic complex was determined using a Sephadex G —75 column after its calibration by dextrans with molecular weight equal to 10,000, 40,000 and 70,000 and rafinose with molecular weight of 504. Fractions were also analyzed by the disk —electrophoresis method in PAAG (7) using 7.5% polyacrilamide gel (pH 4.3). Activity of pectinesterase was determined by titrometric method [8]. The enzymatically released methanol analyzed by gas—liquid chromatography [9]. 

Enzymes play an important role in biochemical analysis. In biological material—e. g in body fluids—even tiny quantities of an enzyme can be detected by measuring its catalytic activity. However, enzymes are also used as reagents to determine the concentrations of metabolites—e.g., the blood glucose level (C). Most enzymatic analysis procedures use the method of spectrophotometry (A). 

How to determine which protein activity should be targeted for drug discovery. For proteins with a clearly defined enzymatic activity, the use of catalytically inactive mutants has been proven to be useful. In the field of protein kinase research, kinase-dead mutants frequently behave as dominant-negatives, thus highlighting the importance of the kinase activity. In addition, the Shokat lab has developed a method allowing validation of the specific contribution of a kinase activity in cellular pathways. 

The use of polysaccharide-based CSPs instead of protein-based CSPs often increases the peak efficiency and facilifafes faster separafions. Papini ef al. [159] recently developed a method for the enantioseparation of lorazepam and on a Chiralpak OD-R column and an enzymatic hydrolysis was used to determine the amount of the glucoronide metabolite of lorazepam present. The separation was performed in 7 min with an LOQ of 1 and 10 ng/mL for lorazepam in plasma and urine, respectively. Another relatively fast separation for chiral analysis was published by Lausecker and Eischer [188]. They developed a method for determination of the drug candidate R483 within... 

By using a commercial diagnostic cholesterol reagent (enzymatic method) and gas chromatography, the cholesterol contents of four different egg yolk preparations (including whole egg powder, fresh, frozen, and dried egg yolk) were determined and compared. 

Many methods have been used to determine organic acids in foods, including volumetric, electrochemical, enzymatic, and chromatographic (paper, thin-layer, gas-liquid, or HPLC) methods. However, most of these are not able to assay organic acids comprehensively for example, the enzymatic methods are specific kits for individual organic acids (i.e., they only detect one of the acids present). Therefore, to analyze the sample comprehensively using enzymatic methods would be extremely time consuming and costly, as the analysis would have to be run separately for each acid and would require several kits. 

Several techniques have been developed for the determination of purine and pyrimidine derivatives in food sample and in particular for hypoxanthine quantification biosensors (220-223) and electrochemical methods making use of immobilized enzyme electrode (224 -227), electrochemical enzymatic-based HA methods (228,229), enzyme reaction with fluorimetric detection (230), radioimmunoassay (231), colorimetric methods (232), capillary electrophoresis (233), and TLC (234). Many HPLC methods have also been developed and are reported in Table 4 (235-247) the most recent ones are described next. 

---