When conducting various experiments, the required purity of  proteins can vary significantly depending on the specific goals, detection methods, and downstream applications. Below is a table summarizing the protein purity requirements for different types of experiments:

While affinity tags (e.g., His-tag, GST-tag) are commonly used to facilitate protein purification, there are scenarios where tag-free proteins are desired, especially for structural studies, therapeutic applications, or functional assays where the tag might interfere with the protein's activity. Here are several strategies to obtain tag-free proteins:

1.  His-Tag (Polyhistidine Tag): 

Protein purification is a critical step in producing recombinant proteins for research, industrial, or therapeutic applications. The goal is to isolate the target protein from a complex mixture of other proteins and impurities. Here are some common protein purification methods:

Choosing the right signal peptide is critical for efficient and accurate protein targeting. Here are some factors to consider: