About cofactors the presence of calcium gave an increment for
olive lipase activity only up to a concentration of 100 mM, whereas
higher concentrations determined a slight positive effect. It is
known that the calcium stimulates castor bean neutral lipase,
which requires micromolar concentrations of calcium [16], and oil
palm lipase [33], which is calcium-dependent. In addition, calcium
ions have been shown to stimulate pancreatic lipase [19], aswell as
many microbial lipases [14]. The stimulating effect of Ca2þ may be
attributed to a better alignment of the enzyme on the substrate
molecule and to the neutralization of fatty acids hydrolyzed from
the substrate molecule [21,13].