柠檬明串珠菌KM20中D-乳酸脱氢酶的特性
作者:
作者单位:

(1. 延边大学农学院,吉林 延吉 133002;2. 延边大学附属医院西区医院,吉林 延吉 133002)

作者简介:

文宇萍,女,延边大学助理实验师,硕士。

通讯作者:

崔虎山(1970—),男,延边大学副主任医师,博士。E-mail: tim-cn@163.com金清(1971—),女,延边大学教授,博士。E-mail: jinqing@ybu.edu.cn

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基金项目:

吉林省科技发展计划技术创新引导项目(编号:20220402053GH);国家自然科学基金地区科学基金项目(编号:31660452)


Characterization of D-lactate dehydrogenase in Leuconostoc citreum KM20
Author:
Affiliation:

(1. College of Agriculture, Yanbian University, Yanji, Jilin 133002, China; 2. College of Affiliated Hospital Western District Hospital, Yanbian University, Yanji, Jilin 133002, China)

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    摘要:

    目的:分析柠檬明串珠菌中D-乳酸脱氢酶(D-LDH)的酶学特性。方法:对柠檬明串珠菌KM20中D-乳酸脱氢酶基因进行克隆表达并构建表达质粒,转化至Escherichia coli BL21(DE3)中实现过表达。结果:经Ni-NTA柱亲和层析纯化后,D-LDH-1与D-LDH-2编码的蛋白分子质量分别为40.0,38.5 kDa;比活力分别为2.18,153.10 U/mg;在丙酮酸还原中两种酶的最适pH值与最适温度均为8.0与40 ℃;而乳酸氧化时D-LDH-2的最适pH值与最适温度分别为12.0与30 ℃。D-LDH-1与D-LDH-2对草酰乙酸、苯丙酮酸和2-酮戊二酸具有较强的催化能力,且Ca2+、Cu2+和Na+对其酶活性均具有促进作用,Zn2+与SDS对酶活性有极高的抑制作用。此外,两种酶对丙酮酸的Km值分别为2.98,6.11 mmol/L,对丙酮酸的Kcat/Km分别为6.04×102,2.28×104 L/(mol·s),LDH-2对D-乳酸的Kcat/Km为65.0 L/(mol·s)。结论:D-LDH-1与D-LDH-2为柠檬酸明串珠菌中催化D-乳酸合成的关键酶。

    Abstract:

    Objective: This study focused on investigating the enzymatic characteristics of D-lactate dehydrogenase (D-LDH) in Leuconostoc citreum KM20. Methods: The D-lactate dehydrogenase gene (LDH) from L.citreum KM20 was cloned and expressed to construct expression plasmid, and then transformed into Escherichia coli BL21 (DE3) for overexpression. Results: The enzymes encoded by LCK_00027 and LCK_00222 were purified by Ni-NTA column affinity chromatography with molecular mass of 40.0 kDa and 38.5 kDa, respectively. The specific activities were 2.18 U/mg and 153.10 U/mg, respectively. The optimal pH and temperature for pyruvate reduction were 8.0 and 40 ℃, respectively, while for the LCK_00222 encoding enzyme lactic acid oxidation the values were 12.0 and 30 ℃, respectively. The two enzymes had high activities toward oxaloacetic acid, sodium phenylpyruvate, and 2-oxoglutaric acid. Ca2+, Cu2+, and Na+ promoted the activity of the two enzymes, whereas Zn2+ and SDS inhibited. In addition, the Kcat/Km of LCK_00027 and LCK_00222 to pyruvate were 6.04×102 L/(mol·s) and 2.28×104 L/(mol·s), respectively. The Kcat/Km of LCK_00222 encoding enzyme to D-lactic acid was 65.0 L/(mol·s). Conclusion: D-LDH-1 and D-LDH-2 are key enzymes catalyzing the synthesis of D-lactic acid in Leuconostoc citrate.

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文宇萍,刘金熙,金 清,等.柠檬明串珠菌KM20中D-乳酸脱氢酶的特性[J].食品与机械,2024,41(2):36-42.
WEN Yuping, LIU Jinxi, JIN Qing, et al. Characterization of D-lactate dehydrogenase in Leuconostoc citreum KM20[J]. Food & Machinery,2024,41(2):36-42.

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  • 收稿日期:2023-06-15
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  • 在线发布日期: 2024-03-27
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