This review examines five Mtb enzymes that contain an active site cysteine residue and are considered as key targets for anti-tuberculosis drugs, namely alkyl hydroperoxide reductase (AhpC), dihydrolipoamide dehydrogenase (Lpd), aldehyde dehydrogenase (ALDH), methionine aminopeptidase (MetAP) and cytochromes P450. The gene discussed is LDHA; the disease is tuberculosis.