Spectrophotometric Assay
Spectrophotometric Assay - Related Videos
09:03
Spectrophotometric Determination of an Equilibrium Constant
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2023
Source: Laboratory of Dr. Michael Evans — Georgia Institute of Technology The equilibrium constant, K, for a chemical system is the ratio of product concentrations to reactant concentrations at equilibrium, each raised to the power of their respective stoichiometric coefficients. Measurement of K involves determination of these concentrations for systems in chemical equilibrium. Reaction systems containing a single colored component can be studied spectrophotometrically. The relation between...
04:00
Spectrophotometric Assay to Determine Glycogen Synthase Activity
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2025
This video describes a spectrophotometric assay for the estimation of glycogen synthase activity. The method relies on the reduction in the absorbance of NADH with time and indicates glycogen synthase activity.
14:57
Spectrophotometric Screening for Potential Inhibitors of Cytosolic Glutathione S-Transferases
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Cited by 14 •
2020
Glutathione S-transferases (GSTs) are detoxification enzymes involved in the metabolism of numerous chemotherapeutic drugs. Overexpression of GSTs is correlated with cancer chemotherapy resistance. One way to counter this phenotype is to use inhibitors. This protocol describes a method using a spectrophotometric assay to screen for potential GST inhibitors.
08:07
Spectrophotometric Determination of Phycobiliprotein Content in Cyanobacterium Synechocystis
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Cited by 42 •
2018
Here, we present a protocol to quantitatively determine phycobiliprotein content in the cyanobacterium Synechocystis using a spectrophotometric method. The extraction procedure was also successfully applied to other cyanobacteria and algae strains; however, due to variations in pigment absorption spectra, it is necessary to test the spectrophotometric equations for each strain individually.
07:59
Spectrophotometric Methods for the Study of Eukaryotic Glycogen Metabolism
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Cited by 1 •
2021
Techniques to measure the activity of key enzymes of glycogen metabolism are presented, using a simple spectrophotometer operating in the visible range.
FAQs
Beer–Lambert law provides a calculation-based route: absorbance is related to concentration through that law. A calibration-curve approach instead uses standards with known concentrations to establish the relationship empirically. The choice between them determines whether concentration is obtained from a law-based relationship or by comparison with measured standards.
Selecting a wavelength defines the light condition under which the sample is measured. Because the spectrophotometer records absorbance for that selected wavelength, wavelength is part of the assay design rather than a minor instrument setting. Keeping this condition appropriate and consistent supports quantitative comparison among standards, samples, or reaction measurements.
An assay can measure either an enzyme or a reaction product, allowing spectrophotometric analysis to support enzyme kinetics. Measuring a reaction product links absorbance to biochemical activity, while measuring the enzyme targets the biological component itself. In biochemistry, these options help researchers investigate reactions and biochemical pathways using quantitative data.
A practical workflow begins by preparing standards when a calibration curve will be used, then measuring their absorbance and the sample absorbance under the selected wavelength. The resulting relationship is used to determine the target concentration. This sequence converts an instrument reading into a quantitative biochemical result rather than a qualitative observation.
Microplate compatibility changes the scale and convenience of the workflow. Instead of restricting measurements to a single sample format, the assay can support analysis in microplate formats, which is useful when many biochemical samples must be handled in a routine experiment. This feature contributes to the method’s speed and relative simplicity.
Spectrophotometric assays are relevant across several biochemical sample types, including proteins, nucleic acids, metabolites, enzymes, and reaction products. Their broad analyte range supports routine analysis and quality control as well as research. In pathway studies, the measurements can provide quantitative information about biochemical components or products associated with those pathways.