The article "PROTEIN MEASUREMENT WITH THE FOLIN PHENOL REAGENT" by Oliver H. Lowry, Nira J. Rosebrough, A. Lewis Farr, and Rose J. Randall discusses the use of the Folin phenol reagent for protein measurement. The reagent, first proposed by Wu in 1922, has been modified and used for various applications, including serum, antigen-antibody precipitates, and insulin. Despite its sensitivity and simplicity, it has not gained widespread acceptance for general biochemical purposes due to its peculiarities and limitations. The authors describe the reagents and procedures for measuring protein in solution or after precipitation, including the effects of pH, reaction time, and reactant concentrations. They also address permissible levels of reagents and interfering substances. The method involves mixing the protein with alkaline copper solution and Folin reagent, followed by colorimetric or spectrophotometric readings. The article provides detailed protocols for both soluble and insoluble proteins, including microanalysis techniques for very small amounts of protein. The discussion highlights the advantages and disadvantages of the Folin reaction, such as its sensitivity, specificity, and ease of adaptation for small-scale analyses. However, it also notes that the color produced varies with different proteins and is not strictly proportional to concentration. The authors suggest reasonable applications for the copper-Folin reaction, including enzyme fractionations, mixed tissue proteins, very small absolute amounts of protein, and large numbers of similar protein samples. Overall, the article provides a comprehensive guide to the use of the Folin phenol reagent for protein measurement, emphasizing its strengths and limitations.The article "PROTEIN MEASUREMENT WITH THE FOLIN PHENOL REAGENT" by Oliver H. Lowry, Nira J. Rosebrough, A. Lewis Farr, and Rose J. Randall discusses the use of the Folin phenol reagent for protein measurement. The reagent, first proposed by Wu in 1922, has been modified and used for various applications, including serum, antigen-antibody precipitates, and insulin. Despite its sensitivity and simplicity, it has not gained widespread acceptance for general biochemical purposes due to its peculiarities and limitations. The authors describe the reagents and procedures for measuring protein in solution or after precipitation, including the effects of pH, reaction time, and reactant concentrations. They also address permissible levels of reagents and interfering substances. The method involves mixing the protein with alkaline copper solution and Folin reagent, followed by colorimetric or spectrophotometric readings. The article provides detailed protocols for both soluble and insoluble proteins, including microanalysis techniques for very small amounts of protein. The discussion highlights the advantages and disadvantages of the Folin reaction, such as its sensitivity, specificity, and ease of adaptation for small-scale analyses. However, it also notes that the color produced varies with different proteins and is not strictly proportional to concentration. The authors suggest reasonable applications for the copper-Folin reaction, including enzyme fractionations, mixed tissue proteins, very small absolute amounts of protein, and large numbers of similar protein samples. Overall, the article provides a comprehensive guide to the use of the Folin phenol reagent for protein measurement, emphasizing its strengths and limitations.