scholarly journals A direct, continuous, sensitive assay for protein disulphide-isomerase based on fluorescence self-quenching

2005 ◽  
Vol 391 (2) ◽  
pp. 351-357 ◽  
Author(s):  
Arun Raturi ◽  
Panayiotis O. Vacratsis ◽  
Dana Seslija ◽  
Lana Lee ◽  
Bulent Mutus
Keyword(s):  
Platelet Surface ◽  
Protein Disulphide Isomerase ◽  
Isomerase Activity ◽  
Single Turnover ◽  
Reduction Activity ◽  
Crude Sample ◽  
Terminal Amino ◽  
Uv Visible ◽  
Continuous Determination

PDI (protein disulphide-isomerase) activity is generally monitored by insulin turbidity assay or scrambled RNase assay, both of which are performed by UV–visible spectroscopy. In this paper, we present a sensitive fluorimetric assay for continuous determination of disulphide reduction activity of PDI. This assay utilizes the pseudo-substrate diabz-GSSG [where diabz stands for di-(o-aminobenzoyl)], which is formed by the reaction of isatoic anhydride with the two free N-terminal amino groups of GSSG. The proximity of two benzoyl groups leads to quenching of the diabz-GSSG fluorescence by approx. 50% in comparison with its non-disulphide-linked form, abz-GSH (where abz stands for o-aminobenzoyl). Therefore the PDI-dependent disulphide reduction can be monitored by the increase in fluorescence accompanying the loss of proximity-quenching upon conversion of diabz-GSSG into abz-GSH. The apparent Km of PDI for diabz-GSSG was estimated to be approx. 15 μM. Unlike the insulin turbidity assay and scrambled RNase assay, the diabz-GSSG-based assay was shown to be effective in determining a single turnover of enzyme in the absence of reducing agents with no appreciable blank rates. The assay is simple to perform and very sensitive, with an estimated detection limit of approx. 2.5 nM PDI, enabling its use for the determination of platelet surface PDI activity in crude sample preparations.

Characterization of Glycoprotein Fraction from Carp Pituitaries Isolated Using Concanavalin A as the Affinity Ligand

1998 ◽  
Vol 63 (3) ◽  
pp. 434-440 ◽  
Author(s):  
Irena Hulová ◽  
Jana Barthová ◽  
Helena Ryšlavá ◽  
Václav Kašička
Keyword(s):  
Concanavalin A ◽  
Reversed Phase ◽  
Amino Acid Sequences ◽  
Gel Chromatography ◽  
Affinity Ligand ◽  
Sds Page ◽  
Terminal Amino ◽  
Α And Β Subunits

Glycoproteins that have affinity to Concanavalin A were isolated from the acetone-dried pituitaries of common carp (Cyprinus carpio L.). Two fractions of glycoproteins were separated using gel chromatography on Superdex 75HR. The fraction with lower molecular weight (30 000) corresponding to the carp gonadotropin cGtH II was composed of two subunits as determined using SDS-PAGE. This protein fraction was further divided into four components using reversed-phase HPLC. Two fractions were pure α and β subunits of cGtH II as follows from immunodetection and from determination of N-terminal amino acid sequences. The other two were a mixture of α and β subunits as was also revealed by N-terminal analysis. Capillary electrophoresis was also used for characterization of isolated glycoproteins.

Continuous Determination of Various Enzymes and Sodium Concentration in Urine

1978 ◽  
Vol 4 (5) ◽  
pp. 334-337 ◽  
Author(s):  
G. Horpacsy ◽  
J. Zinsmeyer ◽  
M. Mebel
Keyword(s):  
Sodium Concentration ◽  
Continuous Determination

Continuous determination of the volume of a space in a non steady state condition

1974 ◽  
Vol 36 (1) ◽  
pp. 59-66
Author(s):  
Oscar A. Gómez-Poviña ◽  
Carmen Sainz de Calatroni ◽  
Susana Orden de Puhl ◽  
Mariano J. Guerrero
Keyword(s):  
Steady State ◽  
State Condition ◽  
Steady State Condition ◽  
Continuous Determination

VALIDATED RP-HPLC AND UV-SPECTROSCOPY METHODS FOR THE ESTIMATION OF DAPAGLIFLOZIN IN BULK AND IN TABLETS

INDIAN DRUGS ◽  
2017 ◽  
Vol 54 (03) ◽  
pp. 44-51
Author(s):  
B. Sabbagh ◽  
B. V. S. Lokesh ◽  
G. A. Akouwah ◽  
Keyword(s):  
Good Accuracy ◽  
Uv Spectroscopy ◽  
Linear Regression Analysis ◽  
Molar Absorptivity ◽  
Hplc Method ◽  
Rp Hplc ◽  
Accuracy And Precision ◽  
Significant Difference ◽  
Uv Visible

Two methods were developed for the determination of dapagliflozin (DAPA) in pure form and in tablets. The procedure utilized was UV-Visible Spectroscopy and RP-HPLC with PDA detector to quantify DAPA in bulk and tablets. The sensitive linear range was identified for both methods within 0.5-5.0μg/mL. The linear regression analysis was identified for both methods with correlation coefficient(r)>0.99. The LOD and LOQ values were found to be 0.05 μg/mL and 0.5 μg/mL for the method by UV-Spectroscopy. The molar absorptivity (ε) was calculated as 1.27 X 105 L.mol-1cm-1. The RP-HPLC method produced LOD and LOQ values of 1.0 ng/mL and 0.5 μg/mL. Both methods were simple, precise, reproducible to quantify the amount of unknown in bulk as well as in tablets and estimated accurately within the range of 100.0±0.5%. Statistical analysis was performed on the data obtained. There was no significant difference between the developed and reported methods with p>0.05. Both methods can be applied for routine analysis of DAPA in bulk and tablets with good accuracy and precision.

scholarly journals DEVELOPMENT AND VALIDATION OF UV-SPECTROPHOTOMETRIC METHOD FOR ESTIMATION OF HYDROQUINONE IN BULK, MARKETED CREAM AND PREAPARED NLC FORMULATION

2017 ◽  
Vol 9 (5) ◽  
pp. 102
Author(s):  
Sukhjinder Kaur ◽  
Taranjit Kaur ◽  
Gurdeep Kaur ◽  
Shivani Verma
Keyword(s):  
Spectrophotometric Method ◽  
Limit Of Detection ◽  
Pharmaceutical Formulations ◽  
Pure Form ◽  
Nanostructured Lipid Carrier ◽  
Limit Of Quantification ◽  
Double Beam ◽  
Uv Visible ◽  
Development And Validation

Objective: The aim of the present work was to develop a simple, rapid, accurate and economical UV-visible spectrophotometric method for the determination of hydroquinone (HQ) in its pure form, marketed formulation as well as in the prepared nanostructured lipid carrier (NLC) systems and to validate the developed method.Methods: HQ was estimated at UV maxima of 289.6 nm in pH 5.5 phosphate buffer using UV-Visible double beam spectrophotometer. Following the guidelines of the International Conference on Harmonization (ICH), the method was validated for various analytical parameters like linearity, precision, and accuracy robustness, ruggedness, limit of detection, quantification limit, and formulation analysis.Results: The obtained results of the analysis were validated statistically. Recovery studies were performed to confirm the accuracy of the proposed method. In the developed method, linearity over the concentration range of 5-40 μg/ml of HQ was observed with the correlation coefficient of 0.998 and found in good agreement with Beer Lambert’s law. The precision (intra-day and inter-day) of the method was found within official RCD limits (RSD<2%).Conclusion: The sensitivity of the method was assessed by determining the limit of detection and limit of quantification. It could be concluded from the results obtained that the purposed method for estimation of HQ in pure form, in the marketed ointment and in the prepared NLC-formulation was simple, rapid, accurate, precise and economical. It can be used successfully in the quality control of pharmaceutical formulations and for the routine laboratory analysis.

Free-base corroles: determination of deprotonation constants in non-aqueous media

2007 ◽  
Vol 11 (04) ◽  
pp. 269-276 ◽  
Author(s):  
Jing Shen ◽  
Zhongping Ou ◽  
Jianguo Shao ◽  
Michał Gałęzowski ◽  
Daniel T. Gryko ◽  
...  
Keyword(s):  
Equilibrium Constants ◽  
Aqueous Media ◽  
Free Base ◽  
Organic Base ◽  
Experimental Conditions ◽  
Spectral Changes ◽  
Base Analysis ◽  
Uv Visible ◽  
The Given

A series of free-base corroles with different electron-donating or electron-withdrawing substituents were reacted with piperidine, 4-aminopyridine, 2-methylimidazole, 2-aminopyridine or pyridine in PhCN and the UV-visible spectral changes monitored during conversion of ( Cor ) H 3 to [( Cor ) H 2]- as a function of the concentration and strength of the added organic base. Analysis of the UV-visible spectral changes as a function of the added base concentration enabled calculation of equilibrium constants ( logK ) for deprotonation of each corrole under the given experimental conditions. Relationships are examined between the experimentally measured logK values and previously published spectroscopic and structural properties of the compounds.

Quantitative determination of platelet surface alloantigens using a monoclonal probe

1986 ◽  
Vol 15 (3) ◽  
pp. 251-262 ◽  
Author(s):  
Marleen Janson ◽  
Janice McFarland ◽  
Richard H. Aster
Keyword(s):  
Quantitative Determination ◽  
Platelet Surface

Design of a novel optical sensor for determination of trace amounts of copper by UV–visible spectrophotometry in real samples

2017 ◽  
Vol 32 (3) ◽  
pp. e4110
Author(s):  
Eslam Pourbasheer ◽  
Somayeh Morsali ◽  
Zhila Azari ◽  
Mohammad Ali Karimi ◽  
Mohammad Reza Ganjali
Keyword(s):  
Optical Sensor ◽  
Real Samples ◽  
Visible Spectrophotometry ◽  
Uv Visible
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