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Quality and lifecycle management
Published in Sarfaraz K. Niazi, Biosimilars and Interchangeable Biologics, 2016
The biuret assay is relatively independent on the protein standard of choice as the reaction chemistry is based on polypeptide structure and not on the composition of the amino acid residue side chains. The sensitivity range is from 0.5 to 10 mg/mL making the assay the least sensitive among the colorimetric assays. The sample may be treated with trichloroacetic acid (TCA) or deoxycholate-trichloroacetic acid in order to precipitate the protein before analysis as most proteins are almost quantitatively precipitated even from dilute solutions. The TCA precipitate should be dissolved in base or appropriate buffer prior to analysis. Samples may also be dialyzed against a suited buffer in order to remove substances interfering with the assay. Desalting is also recommended, but at loss of protein in the range from 10% to 15% should be expected.
Arsenals of Pharmacotherapeutically Active Proteins and Peptides: Old Wine in a New Bottle
Published in Debarshi Kar Mahapatra, Swati Gokul Talele, Tatiana G. Volova, A. K. Haghi, Biologically Active Natural Products, 2020
Biuret Reaction: Proteins react with solution of copper sulfate in sodium hydroxide to form a violet-colored complex [118]. The compound biuret (shown in Figure 2.35) also gives this reaction and hence the name. The intensity of the color formed is directly proportional to the number of peptide bonds and thus, the protein concentration, forming a deep blue-violet complex as shown in Figure 2.39. This test is not given by dipeptides [1]. Biuret reaction is also used for quantitative estimation of proteins by reading absorption at 540 nm [119].
Detection Technology
Published in Rick Houghton, William Bennett, Emergency Characterization of Unknown Materials, 2020
Rick Houghton, William Bennett
The biuret method of protein detection uses biuret reagent, a strongly caustic solution of copper sulfate. This deep blue solution can be diluted with water in a test tube. A small sample may be added to the test tube or the dilute solution may be added directly to a powder on a surface. If protein is present, a purple color (540 nm) will develop from blue. The color change is difficult to see in the case of low concentrations of protein. The result is sensitive to the presence of nitrogen-containing compounds.
Novel treatment of gelatin-copper bio-nanoparticles as a management method against the spiny bollworm, Earias insulana, (Boisd.) (Lepidoptera: Noctuidae) in comparison studies with the uncoated nanoparticles
Published in Inorganic and Nano-Metal Chemistry, 2021
Hala A. Ammar, Eman M. Abd-ElAzeem
Colorimetric determination of total soluble protein in total homogenate of larvae of spiny bollworm was carried out according to Gornall et al.[36] 0.2 ml of larval homogenate was added to 5 ml of Biuret reagent and incubated for 30 min at 20-25 °C. The absorbance of the sample against a blank Biuret reagent was measured at wavelength of 546 nm. Total lipids were estimated by the method of Zollner & Kirch[37] using phosphor vanillin reagent and the released color was estimated at 525 nm against blank. The results were expressed as mg lipids/gm body weight.