Lowry Method
Lowry Method - Related Videos
02:58
Bronsted-Lowry Acids and Bases
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2020
The acid-base reaction class has been studied for quite some time. In 1680, Robert Boyle reported traits of acid solutions that included their ability to dissolve many substances, to change the colors of certain natural dyes, and to lose these traits after coming in contact with alkali (base) solutions. In the eighteenth century, it was recognized that acids have a sour taste, react with limestone to liberate a gaseous substance (now known to be CO2), and interact with alkalis to form neutral...
02:16
Brønsted-Lowry Acids and Bases
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2025
In 1923, the Brønsted–Lowry definition of acids and bases was proposed by Johannes Brønsted and Thomas Lowry. According to this theory, a Brønsted acid is defined as a species that donates a proton in a chemical reaction and gets converted to its conjugate base. A Brønsted base is defined as a species that accepts a proton in a chemical reaction and gets converted into its conjugate acid. These transfers of protons are caused by the displacement of electrons in these reactions, which is...
02:30
Water: A Bronsted-Lowry Acid and Base
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2020
The reaction between a Brønsted-Lowry acid and water is called acid ionization. For example, when hydrogen fluoride dissolves in water and ionizes, protons are transferred from hydrogen fluoride molecules to water molecules, yielding hydronium ions and fluoride ions: Base ionization of a species occurs when it accepts protons from water molecules. In the example below, pyridine molecules, C5NH5, undergo base ionization when dissolved in water, yielding hydroxide and pyridinium ions: The...
06:39
Through-the-Wall Blood Sampling Method to Minimize Sleep Disruption in Clinical Settings
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Cited by 1 •
2025
Here, we present a through-the-wall, minimally invasive method to sample blood during sleep in clinical settings.
08:13
Differential Scanning Calorimetry — A Method for Assessing the Thermal Stability and Conformation of Protein Antigen
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Cited by 117 •
2017
Differential scanning calorimetry measures the thermal transition temperature(s) and total heat energy required to denature a protein. Results obtained are used to assess the thermal stability of protein antigens in vaccine formulations.
FAQs
Alkalinity enables peptide bonds to react with copper ions, creating the copper-protein complex required for the next color-forming stage. This chemical sequence links the amount of protein-associated copper to subsequent reduction of the Folin–Ciocalteu reagent. Without this staged reaction, the assay would not generate the strong color response used for spectrophotometric quantification.
After the copper-protein complex forms, tyrosine and tryptophan residues mainly reduce the Folin–Ciocalteu reagent. This reduction produces the intense blue color measured in the assay. Their contribution explains why the observed signal depends not only on the quantity of protein but also on how the protein’s amino acid composition supports the color-forming reaction.
Interfering substances matter because they can alter the color response independently of the protein content being measured. Consequently, the absorbance may no longer correspond accurately to the sample’s actual protein concentration. This limitation requires researchers to consider sample composition when interpreting results from lysates, purified preparations, or other biochemical solutions.
A typical workflow combines the protein sample with alkaline conditions and copper ions, allowing a copper-protein complex to form. The Folin–Ciocalteu reagent is then added to produce the blue color response. Researchers measure that color spectrophotometrically and compare the result with a protein standard curve to determine the sample’s protein content.
The standard curve provides the reference needed to translate color intensity into protein concentration. Researchers measure standards containing known protein amounts, establish their response relationship, and compare the sample’s spectrophotometric signal with that relationship. This comparison makes the assay quantitative rather than merely indicating that protein is present.
The assay is useful when researchers need protein measurements in cell lysates, purified protein preparations, or biochemical experiments. In these settings, it supports quantitative analysis by converting a reaction-generated color signal into an estimate of protein content. Its usefulness depends on interpreting the measurement alongside possible effects from interfering substances in the sample.