Final answer:
Tandem mass spectrometry is mainly used to determine the identity of a purified protein (option C) by analyzing its mass and sequence, leveraging the advancements in spectrometry that allow the analysis of minute protein samples.
Step-by-step explanation:
Tandem mass spectrometry can be used to determine the identity of a purified protein. Mass spectrometry is a technique that identifies and determines the characteristics of a molecule. Advances in this technology have enabled researchers to analyze very small samples of protein.
For precise protein analysis, researchers often turn to mass spectrometry, which, unlike methods such as Polyacrylamide gel electrophoresis (PAGE) which separates proteins by size or X-ray crystallography and nuclear magnetic resonance (NMR) which analyze the three-dimensional structure of proteins, is used primarily to identify proteins based on their mass and sequence. Moreover, bioinformatic tools and databases play a crucial role in analyzing the vast amount of data obtained from these proteomic studies, helping to match mass spectrometry data to known protein sequences.