目的 鲨烯合酶（squalene synthase，SQS）是三萜化合物合成途径中的关键限速酶，对其蛋白特性进行分析与预测。方法 利用生物信息学相关分析工具对20种《中国药典》2015年版收录中药基原植物SQS的理化性质、结构特征及功能特点进行分析。结果 20种中药基原植物有关各条SQS氨基酸序列，其在氨基酸长度、氨基酸组成、相对分子质量及平均亲水系数方面基本一致；所有的SQS均未发现信号肽；二级结构具有明显的一致性，并且α-螺旋和无规则卷曲是主要的结构元件；所有SQS蛋白均含有4个高度保守的结构域和在氨基酸的C端有1~2个跨膜结构；系统进化树结果与植物系统分类学结果基本一致。结论 这20种中药基原植物的SQS的特性差别不大，进化距离也比较近，显示SQS具有较高的保守性和稳定性。分析结果为SQS的功能和作用机制研究提供依据。

Objective Squalene synthase (SQS) is a key rate limiting enzyme in the triterpenoid biosynthesis pathway. The present study aimed to investigate the protein characteristics and phylogenetics of SQS. Methods The physicochemical properties, structural characteristics and functional characteristics of squalene synthases from 20 Chinese herbal plants included in the 2015 edition of Chinese Pharmacopoeia were analyzed by bioinformatics tools. Results The SQS amino acid sequences from 20 Chinese herbal plants showed strong consistency in amino acid numbers, relative molecular weight, amino acid compositions and grand average of hydropathicity. Signal peptides were not detected in the all SQS proteins. The secondary structure prediction results showed that the amino acid sequence of all squalene synthases had Alpha helix and random coil as the main components. The results revealed SQS proteins existed four highly conserved domains and 1-2 transmembrane regions in the C-terminal. The result of phylogenetic analysis was consistent with that of plant classical taxonomy. Conclusion The protein characteristics of SQSs have less differences among the 20 sequences, and the evolutionary differences are also close, which hint that SQSs have high conservation in evolution. The results provide the basis for the study of SQS function and mechanism.

R282.12

福建省教育厅中青年教师科研项目（JT180138）；福建农林大学科技创新基金资助项目（KFA17580A）