Abstract:

Docosahexaenoic acid-rich phosphatidylserine (DHA-PS) possesses superior health benefits in improving lipid metabolism, protecting the nervous system, and alleviating and improving neurodegenerative diseases. DHA-PS products are mainly extracted from marine organisms, with shallow content, complicated processes, and high cost. To solve this problem, an efficient lipase-mediated solvent-free transesterification reaction system was constructed to prepare DHA-PS with edible algal oil as the DHA donor. The strategies of enriching phosphatidylserine (PS) from the solvent-free system by extraction with methanol and the detection of the fatty acid composition of PS by thin-layer chromatography coupled with gas chromatography were investigated. The experimental results showed that the highest incorporation rate of DHA in PS was 21.7%. The molecular docking results revealed that strong hydrogen bonding and hydrophobic interactions were presented between the substrates (PS and algal oil) and the enzyme, providing a theoretical possibility for transesterification. In addition, the higher affinity indicated that the catalyst preferred DHA over the other fatty acids involved.

Key words: biocatalysis, transesterification, extraction, molecular docking, PS, DHA

摘要：

富含二十二碳六烯酸的磷脂酰丝氨酸（docosahexaenoic acid-rich phosphatidylserine，DHA-PS）在改善脂质代谢、保护神经系统、缓解和改善神经退行性疾病方面具有突出功效。目前DHA-PS产品主要来自海洋生物提取，含量极低、工艺复杂且成本高。为解决该问题，构建了天然来源的藻油为DHA供体、微量液体脂肪酶为催化剂的高效无溶剂酯交换反应体系制备DHA-PS。建立了采用甲醇萃取从无溶剂体系中富集磷脂的方法，并探究了薄层色谱-气相色谱联用检测磷脂中脂肪酸组成。在实验研究基础上，采用分子对接探究了该体系中底物与酶蛋白间的相互作用及脂肪酶对不同脂肪酸的亲和能力。实验结果显示，产物磷脂酰丝氨酸（phosphatidylserine，PS）中DHA的最高掺入率为21.7%。分子对接结果揭示底物PS和藻油与酶蛋白质间存在较强的氢键作用和疏水作用，这为酯交换反应的发生提供了理论基础。此外，脂肪酶（6xok）对目标脂肪酸DHA的亲和力明显高于其他脂肪酸，表明脂肪酶为催化剂、藻油为DHA供体时可与底物PS发生酯交换反应高效制备DHA-PS。

关键词: 生物催化, 酯交换, 萃取, 分子对接, 磷脂酰丝氨酸, 二十二碳六烯酸