Which protein identification technique involves protein-copper chelation leading to a color change?

The technique that involves protein-copper chelation leading to a color change is the Lowry assay. This method is widely used for quantifying proteins in a sample. In the Lowry assay, proteins react with copper ions under alkaline conditions, leading to the formation of a blue-colored complex. This color intensity is proportional to the protein concentration in the sample, allowing for quantification by comparing the sample's absorbance at a specific wavelength to a standard curve.

The Bradford assay, while also used for protein quantification, relies on the binding of Coomassie Brilliant Blue dye to proteins, which results in a color change but does not involve copper chelation. SDS-PAGE is a technique used for separating proteins based on their molecular weight, and mass spectrometry is utilized for determining the mass and structural information of proteins but does not involve a color change due to chelation.

Using such techniques allows researchers to accurately assess protein concentrations and facilitate further experimental procedures.