Abstract
Enzymes are known to be unstable in the absence of any stabilizing agents. Especially, lipase (EC 3.1.1.3) is more unstable than others. Generally, enzymes are said to be stabilized by its substrate or polyols.
Glycerol or the substrate such as olive oil is found to stabilize lipase (from Candida cylindracea) in aqueous solution. For example, lipase is completely inactivated at 50°C for 4h in aqueous solution (100U/ml), however 80% of the lipase activity is preserved in the presence of 3.6M glycerol under the same conditions.
We have investigated the series of glycerol derivatives which would stabilize the lipase in aqueous solution, and found that glycerol poly (oxypropylene) ethers could stabilize lipase more effectively than glycerol. Actually, 97% of the lipase activity was preserved in the presence of 1.05M glycerol poly (oxypropylene) ether (TG-300) under the above conditions.
Poly (oxypropylene) groups as well as hydroxyl groups seem to stabilize lipase cooperatevely. We believe that hydroxyl groups hold some parts of the enzyme, while poly (oxypropylene) groups hold other parts of the enzyme by the hydrophobic bond simultaneously. This type of complex makes lipase to be stabilized in the aqueous solution.
