Tuberculosis (TB), the second leading cause of death worldwide, kills almost 2 million people annually. Agents that target Mycobacterium. tuberculosis, the causative agent of TB, are needed. A key component of the mycobacterial cell wall is the arabinogalactan polysaccharide, which contains galactofuranose residues (Figure). The essential flavoenzyme, uridine 5'-diphosphate (UDP)-galactopyranose mutase (UGM), generates a biosynthetic glycosyl donor required for arabinogalactan assembly. It catalyzes the interconversion of UDP-galactopyranose and UDP-galactofuranose. We synthesized UDP-galactofuranose and used this substrate to illuminate the mechanism of UGM. Our data suggest unprecedented reactivity for flavin cofactors. To discover UGM inhibitors, we developed a high throughput binding assay, and several leads have been identified. The chemistry and biology of galactofuranose residue incorporation and its relevance for inhibiting the process will be discussed.