Fig. (2).

Human butyrylcholinesterase (represented by PDB code 1P0I) has been transformed into an effective cocaine hydrolysis enzyme by protein engineering. The best variant had a k_cat/K_M for (−)-Cocaine 1390 times larger than the wild type enzyme and also less reactive to its natural substrate acetylcholine [42]. The engineered enzyme contains six mutations in the active site, the locations of which are highlighted as black spheres, which accommodate the bulkier substrate and form more favorable hydrogen bonding interactions.