Name a common method used to analyze the purity of GFP post-purification.

SDS-PAGE is a widely used technique for analyzing the purity of proteins, including GFP, after purification. This method separates proteins based on their molecular weight, allowing researchers to visualize the presence of the target protein along with any other contaminants that may have co-purified during the process.

When a sample is loaded onto the gel and subjected to an electric field, proteins migrate through the gel matrix based on size, with smaller proteins moving faster than larger ones. After electrophoresis, the gel can be stained, typically using Coomassie Blue or other specific stains, to detect and quantify the proteins present. The resulting band pattern provides a clear indication of protein purity; a single band indicates high purity, while multiple bands suggest the presence of impurities or other proteins.

This method is advantageous because it provides a quick and relatively straightforward way to assess the purity of the GFP, which is essential for subsequent applications such as fluorescence assays or structural studies. Moreover, SDS-PAGE results can be further analyzed and quantified using densitometry, enhancing the assessment of purity levels post-purification.