Practice: Detecting Proteins

You are working in a research lab studying a novel protein called WIZE. You have two versions of the protein: the standard version (30 kDa) and a version that has been post-translationally modified with a single ubiquitin molecule (which adds ~8.5 kDa to its mass). You accidentally forgot to label your tubes. What is the best and most direct technique to determine which tube contains the larger, ubiquitinated version of WIZE?
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