text: -Photo-methionine is a photo-reactive amino acid derivative of -methionine that was synthetically formed in 2005. Protein are long polymer chains of amino acids; which can range in various structures and sizes. Proteins can interact with each other (protein-protein interactions or PPI) and with these interactions, affects cellular interactions and pathways. Such interactions; in viral fusion and in growth-factor signaling looked promising for antiviral or anti-cancer drugs, so research must be done to understand the interactions. With that, research has begun to prove that proteins function in supramolecular complexes compared to isolated entities. So, scientists Monika Suchanek, Anna Radzikowski, and Christoph Thiele researched that the direct way to study these interactions in the natural environment better was to create a new way of photo-cross-linking proteins; which led to the synthesis of -photo-methionine and in that same study, -photo-leucine.