Activation of Mucor circinelloides lipase in organic medium

An intracellular Mucor circinelloides lipase either in the form of mycelium-bound enzyme, or in the homogeneous and soluble form, was subjected to activation experiments. It was found that some compounds, such as pyridine, diethanolamine (DEtA), triethanolamine (TEtA), and cetylpyridinium bromide, either increase or decrease the synthetic lipase activity in organic solvents, dependently on their concentration. Differential spectrophotometry of the homogeneous lipase dissolved in toluene, indicate that the variation in the enzyme activity results from an interaction of these substances with the indole group(s) of the tryptophan residue(s), situated on the surface of this enzyme. Our results prove that M. circinelloides lipase is activated not only in the aqueous milieu, but also in organic systems. The molecular background of this phenomenon seems to be similar to the interfacial activation of lipases in the aqueous system (namely the ‘lid’-helix translocation), thought the reason is different.