Lowry's Assay: A Classic Protein Measurement Method

Lowry's assay is a widely used protein measurement method that was developed in 1951 by O.H. Lowry and his colleagues at the University of Buffalo. It is a colorimetric assay that measures the total protein content in a sample by determining the amount of protein-bound copper ions, which then react with a Folin-Ciocalteau reagent to produce a blue-colored complex.

Methods and Materials

The Lowry assay is a straightforward method that involves several steps. First, a sample is mixed with a series of reagents, including bovine serum albumin (BSA) standards and a Folin-Ciocalteau reagent. The absorbance of the resulting solution is then measured at 750 nm using a spectrophotometer.

The assay utilizes several reagents, such as bovine serum albumin (BSA), sodium carbonate, sodium potassium tartarate, copper sulfate, and the Folin-Ciocalteau reagent. The Folin-Ciocalteau reagent itself is a mixture of sodium tungstate, sodium molybdate, orthophosphoric acid, concentrated hydrochloric acid, lithium sulphate, bromine water, and sodium hydroxide.

Applications and Interpretation

Lowry's assay is used to measure the total protein content in a variety of samples, from urine to microbial cultures. In the study cited in the search results, the assay was used to determine the levels of urinary peptides in patients with different levels of proteinuria. The researchers found that the levels of urinary peptides were significantly different between normoproteinuria, microproteinuria, and macroproteinuria cases.

The assay has also been used in other contexts, such as determining the protein content in rumen liquor and developing a method for protein measurement in the presence of Triton X-100.

Conclusion

Lowry's assay is a reliable and widely used method for measuring the total protein content in various types of samples. It is a colorimetric assay that utilizes a series of reagents, including bovine serum albumin (BSA) standards and a Folin-Ciocalteau reagent. The assay has been used in various fields, from clinical research to microbiology, and has proven to be a valuable tool for understanding protein content and its relationship to various physiological processes.