Characterization of overexpressed proteins is essential for assessing their quality, and providing input for iterative redesign and optimization. This process is crucial for the development of therapeutic proteins, vaccines, and other biopharmaceuticals. The rapid characterization of secreted recombinant proteins is a key step in this process, enabling the identification of potential issues and the optimization of production conditions. By using advanced mass spectrometry techniques, researchers can quickly and accurately determine the composition and structure of these proteins, facilitating the development of effective and safe biopharmaceuticals.