哈氏弧菌脂酰-ACP合成酶的体外功能

Identification and characterization of acyl-acyl carrier protein synthetase of Vibrio harveyi in vitro

摘要:

[目的]系统鉴定哈氏弧菌脂酰-ACP合成酶（Acyl-ACP synthetase，AasS）以不同链长游离脂肪酸和非脂肪链羧酸作为底物的体外催化反应。[方法]利用非变性蛋白质凝胶电泳和紫外分光光度计法从定性和定量两个方面分析了AasS的体外催化功能与活性。[结果]AasS能够催化不同链长直链的自由脂肪酸合成脂酰-ACP，其中以C6-C12作为底物时活性最高；以羟基脂肪酸作为底物的情况下，AasS催化C8-C14的羟基脂肪酸有较高的活性。非脂肪链羧酸类作为底物的反应中，20种蛋白质氨基酸、苯甲酸和水杨酸均可以作为AasS的底物，合成相应的脂酰-ACP。[结论]本研究系统地证明了哈氏弧菌脂酰-ACP合成酶（AasS）对不同底物的不同催化活性，为生物体内氨基酸代谢和菌黄素合成代谢的研究提供了可行性的分析依据。

关键词:脂酰-ACP合成酶;自由脂肪酸;氨基酸;苯甲酸;水杨酸

Abstract:

[Objective] The aim of this study was to characterize Vibro harveyi acyl-ACP synthetase (AasS) with free fatty acids of different chain length and other carboxylic acids as substrates in vitro. [Methods] We analyzed the catalytic activity of AasS in vitro qualitatively and quantitatively by Urea-PAGE and UV spectrophotometry, respectively. [Results] AasS could catalyze the synthesis of fatty acyl-ACPs using straight chain free fatty acids with different chain length as substrates, and the enzymatic activity was much higher than C6-C12 fatty acids. In the case of 3-hydroxyl fatty acids, AasS showed higher activities to C8-C14 chain length as substrates. Furthermore, AasS could utilize such as 20 amino acids, benzoic acid and salicylic acid as substrates, and all formed corresponding acyl-ACPs. [Conclusion] Vibro harveyi acyl-ACP synthetase (AasS) catalyzed different substrates with different activities, and this finding could provide a reference for analyzing the metabolism of amino acids.

Key words:fatty acyl-ACP synthetase;free fatty acids;amino acids;benzoic acid;salicylic acid