scholarly journals Assay of Poly(3-Hydroxybutyrate) Depolymerase Activity and Product Determination

2006 ◽  
Vol 72 (9) ◽  
pp. 6094-6100 ◽  
Author(s):  
Birgit Gebauer ◽  
Dieter Jendrossek
Keyword(s):  
High Performance ◽  
Ralstonia Eutropha ◽  
Hydrolysis Product ◽  
Hydrolysis Rates ◽  
Product Identification ◽  
Consumption Rates ◽  
Ph Stat ◽  
First Time ◽  
Hydrolysis Of

ABSTRACT Two methods for accurate poly(3-hydroxybutyrate) (PHB) depolymerase activity determination and quantitative and qualitative hydrolysis product determination are described. The first method is based on online determination of NaOH consumption rates necessary to neutralize 3-hydroxybutyric acid (3HB) and/or 3HB oligomers produced during the hydrolysis reaction and requires a pH-stat apparatus equipped with a software-controlled microliter pump for rapid and accurate titration. The method is universally suitable for hydrolysis of any type of polyhydroxyalkanoate or other molecules with hydrolyzable ester bonds, allows the determination of hydrolysis rates of as low as 1 nmol/min, and has a dynamic capacity of at least 6 orders of magnitude. By applying this method, specific hydrolysis rates of native PHB granules isolated from Ralstonia eutropha H16 were determined for the first time. The second method was developed for hydrolysis product identification and is based on the derivatization of 3HB oligomers into bromophenacyl derivates and separation by high-performance liquid chromatography. The method allows the separation and quantification of 3HB and 3HB oligomers up to the octamer. The two methods were applied to investigate the hydrolysis of different types of PHB by selected PHB depolymerases.

Development of an HPLC-UV Method for Quantification of Stattic

2019 ◽  
Vol 15 (6) ◽  
pp. 568-573
Author(s):  
Soheil Sedaghat ◽  
Ommoleila Molavi ◽  
Akram Faridi ◽  
Ali Shayanfar ◽  
Mohammad Reza Rashidi
Keyword(s):  
High Performance ◽  
Accurate Method ◽  
Plasma Samples ◽  
Promising Target ◽  
Relative Standard ◽  
Dimerization Inhibitor ◽  
Oncogenic Protein ◽  
First Time ◽  
Transcription 3

Background: Signal transducer and activator of transcription 3 (STAT3), an oncogenic protein found constitutively active in many types of human malignancies, is considered to be a promising target for cancer therapy. Objective: In this study for the first time, a simple and accurate method has been developed for the determination of a STAT3 dimerization inhibitor called stattic in aqueous and plasma samples. Methods: A reverse-phase high-performance liquid chromatography (RP-HPLC) composed of C18 column as stationary phase, and the mixture of acetonitrile (60%) and water (40%) as mobile phase with a UV detection at 215 nm were applied for quantification of stattic. The developed method was validated by Food and Drug Administration (FDA) guideline. Results: The method provided a linear range between 1-40 and 2.5-40 µg mL-1 for aqueous and plasma samples, respectively, with a correlation coefficient of 0.999. The accuracy (as recovery) of the developed method was found to be between 95-105% for aqueous medium and 85-115% for plasma samples. The precision (as relative standard deviation) for aqueous and plasma samples was less than 6% and 15%, respectively. The sensitivity of the developed method based on FDA guideline was 1 µg mL-1 for aqueous and 2.5 µg mL-1 for plasma samples. Conclusion: These results show that the established method is a fast and accurate quantification for stattic in aqueous and plasma samples.

scholarly journals Kinetics and Mechanism of Hydrolysis of Acetylthiocholine by Butyrylcholine Esterase

2002 ◽  
Vol 57 (11-12) ◽  
pp. 1072-1077 ◽  
Author(s):  
Karel Komers ◽  
Alexandr Čegan ◽  
Marek Link
Keyword(s):  
Acetic Acid ◽  
Kinetics And Mechanism ◽  
Kinetics Parameters ◽  
Mechanism Of Hydrolysis ◽  
Ph Stat ◽  
Stat Method ◽  
Ellman’S Method ◽  
Hydrolysis Of

Kinetics and mechanism of hydrolysis of acetylthiocholine by the enzyme butyrylcholine esterase was studied. The spectrophotometric Ellman’s method and potentiometric pH-stat method were used for continuous determination of the actual concentration of the products thiocholine and acetic acid in the reaction mixture. The validity of the Michaelis-Menten (Briggs-Haldane) equation in the whole course of the reaction under used conditions was proved. The corresponding kinetics parameters (Vm and KM) were calculated from the obtained dependences of concentration of thiocholine or acetic acid vs. time and compared. From this comparison the deciding kinetic role of the step producing thiocholine was derived. The values of initial molar concentration of the enzyme and of the rate constants of the kinetic model were estimated.

Determination of Carbaryl Residues in Honey Bees

1965 ◽  
Vol 48 (4) ◽  
pp. 771-774
Author(s):  
D P Johnson ◽  
H A Stansbury
Keyword(s):  
Aqueous Solution ◽  
Acetic Acid ◽  
Quantitative Determination ◽  
Honey Bees ◽  
Methylene Chloride ◽  
Hydrolysis Product ◽  
Separate Analysis ◽  
Yellow Substance ◽  
Hydrolysis Of

Abstract A method has been developed for detecting residues of carbaryl (1-naphthyl methylcarbamate) as well as its hydrolysis product, 1-naphthol, in dead bees. The method is based on extraction of the bees with benzene, followed by a cleanup involving liquid partitioning and chromatography on Florisil. The quantitative determination involves hydrolysis of carbaryl to 1-naphthol and coupling of the latter with p-nitrobenzenediazonium fluoborate in acetic acid to form a yellow substance. For separate analysis, free 1-naphthol is separated from methylene chloride into a basic aqueous solution. The sensitivity of the method is about 0.1 ppm; recoveries averaged 85.6 ± 6.6% for 1- naphthol and 83.8 ± 2.7% for carbaryl.

scholarly journals Determination of flavones in species of Thymus L. (Lamiaceae) from Macedonian flora

2001 ◽  
Vol 47 ◽  
pp. 9-14
Author(s):  
Svetlana Kulevanova ◽  
Marina Stefova ◽  
Tatjana Kadifkova Panovska ◽  
Jasmina Tonic ◽  
Trajce Stafilov
Keyword(s):  
Ethyl Acetate ◽  
High Performance ◽  
Gradient Elution ◽  
Hplc Method ◽  
Total Flavonoids ◽  
Column Temperature ◽  
Plant Samples ◽  
Layer Chromatography ◽  
Hydrolysis Of

Assay of flavonoids in extracts of seven Thymus L. (Lamiaceae) species from Macedonia including identification and quantification was performed. Extracts obtained after hydrolysis of air dried samples (A1) were analyzed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Luteolin and apigenin were identified in comparison to authentic standard substances. The content of total flavonoids in plant samples determined by UV-Vis spectrometry (with AlCl3) ranged from 0.05-0.13 %. Two other extracts were prepared by extraction with a mixture of ethanol:water (7:3, V/V), evaporation until only water remained and extraction first with diethylether (A2) and secondly with ethyl acetate (A3). The content of flavonoids in diethyl-ether and ethyl acetate extracts ranged from 52.5-244.4 mg·ml-1 and 48.7 -117.5 mg·ml-1, respectively. For quantification of luteolin and total flavonoids the HPLC method was applied, using reverse phase column C18, mobile phase consisting of 5% acetic acid and methanol in gradient elution mode and column temperature set to 40 o C. The content of luteolin in the plant samples ranged from 0.23-0.48 % (m/m), while the content of total flavonoids was found to be 0.26-0.52 %.

Reagent for the enzymatic determination of serum total cholesterol with improved lipolytic efficiency.

1983 ◽  
Vol 29 (6) ◽  
pp. 1075-1080 ◽  
Author(s):  
J Siedel ◽  
E O Hägele ◽  
J Ziegenhorn ◽  
A W Wahlefeld
Keyword(s):  
Total Cholesterol ◽  
Cholesterol Ester ◽  
High Performance ◽  
Serum Lipids ◽  
Serum Total Cholesterol ◽  
Enzymatic Determination ◽  
Layer Chromatography ◽  
Chloroform Methanol ◽  
Hydrolysis Of

Abstract We describe a sensitive method for quantifying the extent of cholesterol ester cleavage during enzymatic assay of total cholesterol in serum. Lipids are extracted from the assay mixture with chloroform/methanol (1/1 by vol), concentrated, then quantified by "high-performance" thin-layer chromatography. Although with conventional enzymatic reagents for determination of serum total cholesterol the hydrolysis of the cholesterol esters may be incomplete, a new enzymatic cholesterol reagent (Monotest Cholesterol, High Performance, Boehringer Mannheim) gives virtually complete cholesterol ester cleavage (i.e., greater than or equal to 99.5%). Use of this reagent with its improved lipolytic efficiency yields results for serum total cholesterol that are identical to those measured with a candidate reference procedure involving alkaline cholesterol ester saponification.

scholarly journals Electro-catalytic amplified sensor for determination of N-acetylcysteine in the presence of theophylline confirmed by experimental coupled theoretical investigation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohsen Keyvanfard ◽  
Hassan Karimi-Maleh ◽  
Fatemeh Karimi ◽  
Francis Opoku ◽  
Ephraim Muriithi Kiarii ◽  
...  
Keyword(s):  
Theoretical Investigation ◽  
High Performance ◽  
Carbon Paste ◽  
Linear Dynamic ◽  
Oxidation Potentials ◽  
Adsorption Energies ◽  
First Time ◽  
Modify Carbon ◽  
Paste Electrode

AbstractThe 1,l/-bis(2-phenylethan-1-ol)ferrocene, 1-butyl-3-methylimidazolium hexafluoro phosphate (BMPF6) and NiO-SWCNTs were used to modify carbon paste electrode (BPOFc/BMPF6/NiO-SWCNTs/CPE), which could act as an electro-catalytic tool for the analysis of N-acetylcysteine in this work. The BPOFc/BMPF6/NiO-SWCNTs/CPE with high electrical conductivity showed two completely separate signals with oxidation potentials of 432 and 970 mV for the first time that is sufficient for the determination of N-acetylcysteine in the presence of theophylline. The BPOFc/BMPF6/NiO-SWCNTs/CPE showed linear dynamic ranges of 0.02–300.0 μM and 1.0–350.0 μM with the detection limit of ~ 8.0 nM and 0.6 μM for the measurement of N-acetylcysteine and theophylline, respectively. In the second part, understanding the nature of interaction, quantum conductance modulation, electronic properties, charge density, and adsorption behavior of N-acetylcysteine on NiO–SWCNTs surface from first-principle studies through the use of theoretical investigation is vital for designing high-performance sensor materials. The N-acetylcysteine molecule was chemisorbed on the NiO–SWCNTs surface by suitable adsorption energies (− 1.102 to − 5.042 eV) and reasonable charge transfer between N-acetylcysteine and NiO–SWCNTs.

Multi-residue determination of micropollutants in Nigerian fish from Lagos lagoon using ultrasound assisted extraction, solid phase extraction and ultra-high-performance liquid chromatography tandem mass spectrometry

2020 ◽  
Vol 12 (16) ◽  
pp. 2114-2122
Author(s):  
Idera Fabunmi ◽  
Natalie Sims ◽  
Kathryn Proctor ◽  
Aderonke Oyeyiola ◽  
Temilola Oluseyi ◽  
...  
Keyword(s):  
High Performance ◽  
Solid Phase ◽  
Ultrasound Assisted Extraction ◽  
Residue Determination ◽  
Chromatography Tandem Mass Spectrometry ◽  
Assisted Extraction ◽  
Liquid Chromatography Tandem Mass ◽  
Lagos Lagoon ◽  
First Time

This reports for the first time a simple and robust approach in determining pharmaceuticals in different fish species in Nigeria.

Spectrophotometric Determination of Decamethrin and Its Residues in Insecticidal Formulations and in Water

1994 ◽  
Vol 77 (3) ◽  
pp. 748-751 ◽  
Author(s):  
R V Prabhakara Raju ◽  
R Raghava Naidu
Keyword(s):  
Spectrophotometric Determination ◽  
Hydrolysis Product ◽  
Spectrophotometric Methods ◽  
Alkaline Conditions ◽  
The Relationship ◽  
Hydrolysis Of

Abstract Three spectrophotometric methods were developed for the microdetermination of decamethrin in insecticidal formulations and in water. The methods are based on the hydrolysis of decamethrin with methanolic KOH to 3-phenoxybenzaldehyde; condensation of the hydrolysis product with 2,4- dinitrophenylhydrazine (2,4-DNPH), 4-nitrophenylhydrazine (4-NPH), or 2,4,6-trinitrophenylhydrazine (2,4,6-TNPH) under alkaline conditions; and measurement of the condensates at the absorption maxima of 444,535, and 480 nm, respectively. The relationship between absorbance and concentration was linear in the ranges of 0.1–5.0 μg/mL, 0.5–7.0 μg/mL and 0.1–5.5 μg/mL for 2,4-DNPH, 4-NPH, and 2,4,6-TNPH, respectively. The methods are sufficiently sensitive and can be used to detect decamethrin at concentrations as low as 0.1 μg/mL.

Sign in / Sign up

Export Citation Format

Share Document