Which method primarily focuses on quantifying proteins in a sample?

The method that primarily focuses on quantifying proteins in a sample is the enzyme-linked immunosorbent assay, commonly known as ELISA. This technique utilizes specific antibodies to detect and measure the concentration of proteins within a sample. ELISA is widely used because of its sensitivity and specificity, allowing for accurate quantification even in samples where the protein of interest is present at low concentrations.

During the ELISA process, the target protein is first attached to a solid surface, usually a microplate. Then, a solution containing a specific antibody is added, which binds to the target protein. A secondary enzyme-linked antibody is subsequently introduced, which binds to the first antibody. When a substrate for the enzyme is added, a measurable signal, such as color change or fluorescence, is produced, which correlates with the amount of protein present in the original sample. This quantification can then be compared against a standard curve.

In contrast, the other methods listed do not primarily focus on quantifying proteins. Gel electrophoresis generally separates proteins based on their size or charge but does not provide a direct quantification. Protein precipitation is a technique used to isolate proteins from a solution but does not quantify them directly. DNA sequencing is focused on determining the sequence of nucleotide bases in