Lowrymääritys

Lowrymääritys, often referred to as the Lowry method, is a biochemical assay used to determine the total concentration of protein in a solution. Developed by Oliver H. Lowry and his colleagues in 1951, it is a colorimetric assay, meaning it relies on a color change that is proportional to the amount of protein present.

The method is based on the reduction of the Folin-Ciocalteu reagent by certain amino acid residues in proteins, particularly tyrosine and tryptophan, in the presence of copper ions under alkaline conditions. This reduction results in the formation of a blue-colored complex. The intensity of the blue color, measured spectrophotometrically at a wavelength of approximately 750 nm, is then compared to a standard curve generated using known concentrations of a protein such as bovine serum albumin (BSA).

The Lowry method is known for its sensitivity and is capable of detecting protein concentrations in the range of micrograms per milliliter. However, it is also known to be affected by the presence of various substances that can interfere with the color development or react with the Folin-Ciocalteu reagent themselves. These interferents include reducing agents, certain buffers, and carbohydrates. Despite these limitations, the Lowry assay remains a widely used and valuable tool in protein quantification, particularly in research settings where its sensitivity is advantageous. Its historical significance and widespread application have made it a foundational technique in biochemistry and molecular biology.