As a chemical biologist I am interested in answering immunological questions using organic chemistry. The question I am currently interested in is how the metabolism of Vitamin A/retinol influences the mucosal immune system. Retinol is converted to retinoic acid (RA) by RALDH. RA is the active metabolite of retinol and induces gut homing and regulatory functions in T and B cells. To study what factors influence RALDH expression I synthesize chemical probes for activity based protein profiling (ABPP). These probes bind covalently with the enzyme via reactive residues in the active site and can then be visualized using click-chemistry.