Exploring the specific features of interfacial enzymology based on lipase studies

Structural basis for the recruitment and activation of the Legionella phospholipase VipD by the host GTPase Rab5

“…A hallmark feature of many phospholipases is to be minimally active on monomeric lipid substrates but undergo a substantial activation on binding to the surface of phospholipid membranes or micelles, a phenomenon known as interfacial activation (28)(29)(30)(31). This behavior has been attributed to a flexible lid that at the lipid-water interface facilitates substrate diffusion to the catalytic site rather than being allosterically modulated through distant ligand binding (25).…”

Effective Kinetic Methods and Tools in Investigating the Mechanism of Action of Specific Hydrolases

“…Although, there is little homology among the known sequences of lipases, however, there are evidences indicating the convergent nature of the catalytic motifs of serine proteases and lipases (Ollis et al, 1992). Another feature of lipases which has been identified as essential for hydrolysis in nonaqueous media, is a surface loop, the lid domain, which covers the active site of lipases (Aloulou et al, 2006). Mechanistic features, similar to those of serine proteases, have been reported also for lipases, as it is the oxyanion hole, although its development differs in these enzymes due to their structural particularities (Aloulou et al, 2006).…”

“…However, it is essential to show that the mechanism of fatty acid ester hydrolysis by lipases in micelles, small aggregates or emulsion particles is noticeably different. It should be emphasized that Michaelis-Menten kinetics is applied only in isotropic reaction media, and thus alternative models have been suggested comprising two steps, i.e., a physical adsorption of lipase at the aqueous/lipid interface leads to its activation (opening of the lid) and the formation of the enzyme-substrate complex, and then, the hydrolytic reaction give the products and the adsorbed free enzyme (Aloulou et al, 2006;1994;Verger & de Haas, 1976). Actually, a twodimensional Michaelis-Menten catalytic step occurs when the soluble lipase (E) is adsorbed on the aqueous/lipid interface (E*) and binds a substrate molecule resulting the development of the E*S complex; then, the soluble product P* is immediately diffused in the water layer (P).…”

“…Another feature of lipases which has been identified as essential for hydrolysis in nonaqueous media, is a surface loop, the lid domain, which covers the active site of lipases (Aloulou et al, 2006). Mechanistic features, similar to those of serine proteases, have been reported also for lipases, as it is the oxyanion hole, although its development differs in these enzymes due to their structural particularities (Aloulou et al, 2006). Recently, a full mechanism of action for the lipase from bovine pancreas (PPL) has been reported and it is analogous to this reported for serine proteases (figure 4a) (Kokkinou et al, 2011).…”

“…. Illustration of a water soluble lipase catalyzing an interfacial reaction, acting on an insoluble substrate; the asterisk denotes species onto the lipid/water interface, and E, S, E*S, and P are the free enzyme, free substrate, enzyme-substrate complex and product, respectively, while k p and k d are constants associated with the adsorption/desorption of enzyme between aqueous and lipid/water interface (modified from Aloulou et al, 2006).…”