Abstract
The small quantities of protein required for mass spectrometry (MS) make it a powerful tool to detect binding (protein–protein, protein–small molecule, etc.) of proteins that are difficult to express in large quantities, as is the case for many intrinsically disordered proteins. Chemical cross-linking, proteolysis, and MS analysis, combined, are a powerful tool for the identification of binding domains. Here, we present a traditional approach to determine protein–protein interaction binding sites using heavy water (18O) as a label. This technique is relatively inexpensive and can be performed on any mass spectrometer without specialized software.
