Using 5-Hydroxytryptophan as a Probe to Follow Protein-Protein Interactions and Protein Folding Transitions

5-Hydroxytyptophan is a fluorescent tryptophan analog that can be incorporated into recombinant proteins expressed in E. coli and is particularly useful in studies of biological systems that involve supermolecular aggregates of more than one protein. Here we review the varied applications of 5-hydroxytryptophan to study structure, interactions, conformational change and dynamics in complex protein systems.