Which technique is primarily used to analyze the size of proteins?

SDS-PAGE, or Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis, is a widely used technique for determining the size of proteins. This method operates on the principle of gel electrophoresis, where proteins are separated based on their molecular weight. The process involves denaturing the proteins using SDS, which gives them a negative charge proportional to their length. When an electric current is applied, the proteins migrate through a polyacrylamide gel; smaller proteins move faster and travel further through the gel matrix than larger ones. By comparing the distance traveled by the proteins to a set of known molecular weight markers, one can accurately assess their sizes.

Gas chromatography, high-performance liquid chromatography, and electrophoresis are different analytical techniques with distinct applications. Gas chromatography is primarily used for volatile compounds, while high-performance liquid chromatography is more suitable for separating smaller molecules or compounds in liquid phases. Electrophoresis is a broader term that encompasses various techniques for separating biomolecules, but SDS-PAGE specifically targets protein size analysis in a gel format. Thus, SDS-PAGE is the ideal choice for precisely analyzing protein sizes.