Molecular Structures and Catalytic Mechanism of Bacterial Lipases

Bacteria produce lipases, which can catalyze both the hydrolysis and the synthesis of long chain triglycerides. These reactions usually proceed with high regioselectivity and enantioselectivity, and, therefore, lipases have become very important biocatalysts used in organic chemistry. 3D lipase structures were solved from several bacterial lipases. They have an α/β hydrolase fold and a catalytic triad consisting of a nucleophilic serine, and an aspartate or glutamate residue that is hydrogen bonded to a histindine. Active sites are covered with α-helical lid structure, of which movement is involved in the enzyme's activation at oil/ water interface. Four substrate binding pockets were identified for triglycerides: an oxyanion hole and three pockets accommodating the fatty acids bound at positions sn-1, sn-2, and sn-3. These pockets determine the enantiopreference of a lipase. The understanding of structure-function relationships as well as the development of molecular evolution techniques will enable researchers to tailor new lipases for biotechnological applications.