Lipase Mediated Interesterification of Triglycerides

脂肪分解酶催化修饰甘油三酯的研究正在进行中。其目的是清楚地描述脂肪酶在最低含水率体系中对脂肪底物的酶促作用。将对两种模型甘油三酯进行酯交换实验，三棕榈素和三油酸酯是涉及脂肪酶修饰脂肪的反应的一个具体例子。实验将考察和比较底物-酶接触的两种不同模式(A)通过有机溶剂中的酶反应，和(B)通过两相反胶束溶液中的酶反应。这些研究将旨在确定在基本非水体系中最佳脂肪酶活性的条件，同时保持对酯交换的高选择性而不是水解性。有机溶剂的作用、水含量和缓冲离子强度的影响、脂酶效应、底物特性和阳离子水平都是需要考虑的各种系统参数。将根据修改后的溶解度参数标准，建立优化溶剂设计和选择的热力学框架。气相色谱的最新发展将应用于热稳定毛细管柱和柱上进样技术，以促进甘油三酯混合物的快速分析。脂肪酶传统上被认为具有通过水解分解甘油三酯的能力。因此，它们被广泛研究，因为它们与动脉粥样硬化的医学相关性以及它们与从植物油中生产长链脂肪酸的工业相关性。直到最近几年，人们才认识到它们在低含水率系统中有效发挥作用的能力。在这种情况下，脂肪酶的作用是一种脂质的合成和修饰，而不是脂肪的分解。脂肪酶催化生物降解和生物合成几种对制药、食品和特种化学品工业非常重要的油脂化学品具有巨大的可能性。例如，酯的合成在生物相容表面活性剂的生产中有应用，这些表面活性剂在食品、化妆品和药品中作为乳化剂是重要的。酯交换反应是目前研究的重点，它涉及两种甘油三酯之间的脂肪酸交换，并直接应用于生产高价值的食用油，如可可脂替代品。对脂肪酶在脂质修饰中的作用的了解仍然有限，其目的是通过对特定反应的综合研究来进一步了解这一点。脂肪酶研究的长期方向将集中在将通过该项目获得的基础知识应用于各种涉及脂类修饰和合成的新反应。

Research into the catalytic modification of triglycerides by lipolytic enzymes is underway. The objective is to clearly delineate the enzymatic action of lipases on lipid substrates in systems with minimal water content. Experiments will be conducted on the interesterification of two model triglycerides, tripalmitin, and triolein, a specific example of a reaction involving lipid modification by lipases. The experiments will examine and compare two alternate modes of substrate-enzyme contact (a) through enzymic reaction in organic solvents, and (b) through enzymic reaction in biphasic reversed micellar solutions. The studies will be directed to determine conditions for optimal lipase activity in essentially non-aqueous systems, with maintenance of a high selectivity to interesterification over hydrolysis. The role of organic solvents, the effects of water content and buffer ionic strength, colipase effects, substrate specificities, and cation levels are various system parameters to be considered. A thermodynamic framework for optimal solvent design and selection will be developed, based on modified solubility parameter criteria. Recent developments in gas chromatography will be applied involving heat-stable capillary columns and on-column injection techniques, to facilitate rapid analyses of triglyceride mixtures. Liapases have traditionally been recognized for their ability to break down triglycerides through hydrolysis. They have, therefore, been studied extensively for their medical relevance to atheroschlerosis and their industrial relevance to the production of long chain fatty acids from vegetable oils. It is only in recent years that their ability to function effectively in low water content systems has been recognized. Under such conditions, lipase action is one of lipid synthesis and modification, rather than lipid breakdown. Tremendous possibilities exist for lipase catalyzed biomodification and biosynthesis of several oleochemicals of importance to the pharmaceutical, food, and specialty chemicals industries. The synthesis of esters for example, has applications to the production of biocompatible surfactants that are important as emulsifiers in food, cosmetics, and pharmaceuticals. The interesterification reaction, the focus of the present research, involves fatty acid interchange between two triglycerides and has direct application to the production of high value edible oils, such as cocoa butter substitutes. The understanding of lipase action in lipid modification is still limited; it is the objective to further this understanding through a comprehensive study of a specific reaction. Long term directions for the research on lipases will focus on applying the fundamental knowledge acquired through this project to a variety of novel reactions involving lipid modification and synthesis.