水溶液中における遊離及び固定化リパーゼの安定化

抄録

Useful methods for the stabilization of lipase (EC 3.1.1.3) in an aqueous solution and in the immobilized insoluble state are presented. (NH₄)₂SO₄ was found to have no effect on lipase stabilization in a range up to 10%. However, such effect was quite prominent at 20% concentration to give 66% of the initial activity indicated (200 units per mL) after 100 days of storage at 35°C (Fig.-2). The intensity of this effect became 1.5 times as much following the addition of a small amount of Na₂SO₃ (0.25%). Essentially the same results were observed for solution mixtures of 20% Na₂SO₄ and 0.25% Na₂SO₃ (Fig.-3). This salt effect was exerted to a greater extent than in the case of polyols and their derivatives (Table-1).
A number of carriers which adsorb lipase were tested for lipase activity (Table-2). Among them, Amberlite CG-50 on which lipase was bound covalently in 50% yield based on lipase activity was found to maintain about 60% the initial activity with 270 days of storage at 35°C (Fig.-4). Basically the same was noted for the lipase absorbed on Amberlite CG-50 in 42.8% yield (Fig.-4). The reason for the high stability of lipase immobilized on Amberlite CG-50 may possibly be the suitable carrier structure on which lipase is adsorbed without losing its three dimensional enzyme moiety and also the balanced hydrophilic and lipophilic carrier properties which facilitate the approach of the substrate (olive oil) onto the carrier surface.
The two practical and simple methods of lipase stabilization presented in this report may serve to promote the field of biotechnology in which lipases are used.