scholarly journals Enzymatic Reactions in a Lab-on-Valve System: Cholesterol Evaluations

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2890 ◽  
Author(s):  
Jucineide S. Barbosa ◽  
Marieta L.C. Passos ◽  
M. das Graças A. Korn ◽  
M. Lúcia M.F.S. Saraiva
Keyword(s):  
Cholesterol Oxidase ◽  
Analytical Tool ◽  
Cholesterol Esterase ◽  
Sequential Injection Analysis ◽  
Enzymatic Reactions ◽  
Waste Generation ◽  
Serum Samples ◽  
Real Samples ◽  
Reagent Consumption ◽  
Alternative Methodology

The micro sequential injection analysis / lab-on-valve (µSIA-LOV) system is a miniaturized SIA system resulting from the implementation of a lab-on-valve (LOV) atop of the selection valve. It integrates the detection cell and the sample processing channels into the same device, promoting the reduction of reagent consumption and waste generation, the improvement of the versatility, and the reduction of the time of analysis. All of these characteristics are really relevant to the implementation of enzymatic reactions. Additionally, the evaluation of cholesterol in serum samples is widely relevant in clinical diagnosis, since higher values of cholesterol in human blood are actually an important risk factor for cardiovascular problems. An automatic methodology was developed based on the µSIA-LOV system in order to evaluate its advantages in the implementation of enzymatic reactions performed by cholesterol esterase, cholesterol oxidase and peroxidase. Considering these reactions, the developed methodology was also used for the evaluation of cholesterol in human serum samples, showing reliable and accurate results. The developed methodology presented detection and quantification limits of 1.36 and 4.53 mg dL−1 and a linear range up to 40 mg dL−1. This work confirmed that this µSIA-LOV system is a simple, rapid, versatile, and robust analytical tool for the automatic implementation of enzymatic reactions performed by cholesterol esterase, cholesterol oxidase, and peroxidase. It is also a useful alternative methodology for the routine determinations of cholesterol in real samples, even when compared with other automatic methodologies.

scholarly journals Enzymatic assay of d-mannose in serum

1997 ◽  
Vol 43 (3) ◽  
pp. 533-538 ◽  
Author(s):  
James R Etchison ◽  
Hudson H Freeze
Keyword(s):  
Bacillus Stearothermophilus ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Enzymatic Assay ◽  
Enzymatic Reactions ◽  
Reaction Products ◽  
Serum Samples ◽  
Healthy Human ◽  
Human Volunteers ◽  
Chromatography Step

Abstract We describe a new and improved enzymatic assay for determining the concentration of d-mannose in sera. Serum d-glucose is selectively converted to glucose-6 phosphate with the highly specific thermostable glucokinase (EC 2.7.1.2) from Bacillus stearothermophilus. The anionic reaction products and excess substrates are removed by a rapid and simple anion-exchange chromatography step in microcentrifuge spin columns. d-Mannose in the glucose-depleted sample is then assayed spectrophotometrically by using coupled enzymatic reactions. The quantitative elimination of glucose from the serum samples allowed the accurate and reproducible assay of serum mannose in the 0–200 μmol/L range. Recovery of mannose added to serum (5–200 μmol/L) was 94% ± 4.4%. The intraassay CV was 6.7% at 40 μmol/L mannose (n = 5; 39.6 ± 1.6 μmol/L) and 4.4% at 80 μmol/L (n = 11; 75.0 ± 1.8 μmol/L); the interassay CV at these concentrations was 12.2% (n = 7; 36.9 ± 2.1 μmol/L) and 9.8% (n = 7; 74.2 ± 2.7 μmol/L), respectively. Sera from 11 healthy human volunteers contained an average of 54.1 ± 11.9 μmol/L mannose (range 36–81 μmol/L).

scholarly journals A simple method for the determination of the cholesterol esterase activity.

2013 ◽  
Vol 60 (3) ◽  
Author(s):  
Agnieszka Ewa Stępień ◽  
Mykhailo Gonchar
Keyword(s):  
Human Serum ◽  
Esterase Activity ◽  
Cholesterol Oxidase ◽  
Cholesterol Esterase ◽  
Cholesterol Esters ◽  
Simple Method ◽  
Bacterial Enzyme ◽  
Low Costs ◽  
Hydrolysis Of

The proposed method determines the activity of cholesterol esterase (CEH) and takes advantage of its ability to catalyze the hydrolysis of cholesterol esters naturally present in human serum. The assay is based on Allain's method of spectrophotometric determination of cholesterol by means of cholesterol oxidase, peroxidase, but using 3,5-dichloro-dihydroxybenzenesulfonic acid (DHBS) as phenolic chromogen and human serum as a source of substrate for the CEH as a novelty. Furthermore, it is characterized by low costs and high precision. It can be employed to control the activity of CE preparations used for the preparation of enzymatic kits for the determination of cholesterol or for screening of potential bacterial enzyme producers.

Direct Fluorometric Determination of Total Cholesterol in Serum Using Derivatized Cholesterol Oxidase

2000 ◽  
Vol 54 (8) ◽  
pp. 1157-1162 ◽  
Author(s):  
Javier Galbán ◽  
José F. Sierra ◽  
José M. López Sebastian ◽  
Susana de Marcos ◽  
Juan R. Castillo
Keyword(s):  
Blood Serum ◽  
Total Cholesterol ◽  
Cholesterol Oxidase ◽  
Enzymatic Reaction ◽  
Direct Determination ◽  
Analytical Signal ◽  
Cholesterol Concentration ◽  
Serum Samples ◽  
Response Range

In this paper the use of cholesterol oxidase derivatized with a fluorescein derivative is proposed for the direct determination of total cholesterol in blood serum. The method is based on the changes in the fluorescence of the solution during the enzymatic reaction (λexe = 498 nm and λem 519 nm). A mathematical model which relates the analytical signal to the total cholesterol concentration was developed, and the model can also be used to obtain some of the thermodynamic constants of the process. The method has a linear response range up to 70 mg/L of cholesterol, a detection limit of 2.5 mg/L, and the precision was 1.0% (40 mg/L cholesterol, n = 10). The method was applied to total cholesterol determination in blood serum samples. The results were compared to those obtained by a commercial analyzer, and statistically similar results were obtained. The use of derivatized cholesterol oxidase makes it possible to simplify the methodology normally used in this type of determination (the indicator reaction is avoided and the number of reagents reduced), with the added advantage that the analytical signal is independent of the concentrations of O2 and cholesterol oxidase.

An enzymatic assay for determining free and total cholesterol in tissue.

1978 ◽  
Vol 24 (3) ◽  
pp. 433-435 ◽  
Author(s):  
J L De Hoff ◽  
L M Davidson ◽  
D Kritchevsky
Keyword(s):  
Total Cholesterol ◽  
Rat Liver ◽  
Ferric Chloride ◽  
Cholesterol Oxidase ◽  
Enzymatic Assay ◽  
Cholesterol Esterase ◽  
Enzymatic Method ◽  
Liver Lipids

Abstract We describe a method for determining free and total cholesterol in extracts of rat-liver lipids by use of a cholesterol esterase/cholesterol oxidase enzymatic kit (Boehringer Mannheim Corp). The lipids are solubilized (as micelles) directly into the aqueous reagent mixture. Results of the enzymatic method correlate well with those obtained by an acid/ferric chloride assay of digitonin precipitates of the extracts. The enzymatic assay of free and total cholesterol in tissue offers advantages of simplicity over previously used methods.

An amperometric FIA system with carrier recycling: an environmentally friendly approach for atenolol determination in pharmaceutical formulations

2016 ◽  
Vol 8 (48) ◽  
pp. 8420-8426 ◽  
Author(s):  
M. A. Franco ◽  
D. A. G. Araújo ◽  
L. H. Oliveira ◽  
M. A. G. Trindade ◽  
R. M. Takeuchi ◽  
...  
Keyword(s):  
Environmentally Friendly ◽  
Pharmaceutical Formulations ◽  
Waste Generation ◽  
Carrier Solution ◽  
Reagent Consumption ◽  
Environmentally Friendly Approach

Carrier solution recirculation in an amperometric FIA system allows ATN quantification with very low reagent consumption and waste generation.

Flow-based food analysis: an overview of recent contributions

2017 ◽  
Vol 9 (45) ◽  
pp. 6313-6334 ◽  
Author(s):  
Milton K. Sasaki ◽  
Fábio R. P. Rocha ◽  
Alex D. Batista ◽  
Diogo L. Rocha
Keyword(s):  
High Precision ◽  
Food Analysis ◽  
Sampling Rate ◽  
Waste Generation ◽  
Food And Beverages ◽  
Flow Systems ◽  
Reagent Consumption

Analysis of food and beverages (e.g.determination of nutrients, additives, and contaminants) is benefited by the advantages provided by flow systems such as high precision and sampling rate, as well as low reagent consumption and waste generation.

scholarly journals Label-free detection of Phytophthora ramorum using surface-enhanced Raman spectroscopy

The Analyst ◽  
2015 ◽  
Vol 140 (21) ◽  
pp. 7254-7262 ◽  
Author(s):  
Sezin Yüksel ◽  
Lydia Schwenkbier ◽  
Sibyll Pollok ◽  
Karina Weber ◽  
Dana Cialla-May ◽  
...  
Keyword(s):  
Surface Enhanced Raman Spectroscopy ◽  
Analytical Tool ◽  
Phytophthora Ramorum ◽  
Label Free ◽  
Specific Detection ◽  
Real Samples ◽  
Label Free Detection ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Species Specific

Label-free and species-specific detection of the plant pathogen Phytophthora ramorum from real samples employing SERS as an analytical tool.

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