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›› 2006, Vol. 6 ›› Issue (3): 458-461.

• 生化工程专栏 • 上一篇    下一篇

Bacillus subtilis NX-2合成g-聚谷氨酸的立体构型调控机理

吴群,徐虹,许琳   

  1. 南京工业大学制药与生命科学学院
  • 出版日期:2006-06-20 发布日期:2006-06-20

Regulation of Stereochemical Composition of Poly-g-glutamic Acid in Bacillus subtilis NX-2

WU Qun,XU Hong,XU Lin   

  1. College of Life Science and Pharmacy,Nanjing University of Technology
  • Online:2006-06-20 Published:2006-06-20

摘要: 探讨了在Bacillus subtilis NX-2发酵生产g-聚谷氨酸(g-PGA)过程中,Mn2+对g-PGA结构中D-和L-谷氨酸组成的影响及其与催化L-谷氨酸生成D-谷氨酸的两个相关酶?谷氨酸消旋酶和D-氨基酸转氨酶之间的关系. 当Mn2+浓度由0增加到0.09 g/L时,D-谷氨酸比例从18%增加到77%;谷氨酸消旋酶活性从0.200 U/mg变为0.441 U/mg,提高了1倍多,D-氨基酸转氨酶活性则几乎没有变化. 说明谷氨酸消旋酶参与了L-到D-谷氨酸的转化过程,且Mn2+是通过改变谷氨酸消旋酶的活性来调节产物g-PGA的立体组成的,这与目前报道的枯草芽孢杆菌合成g-PGA过程中Mn2+浓度与g-PGA中D-, L-构型比无关的结果不同. 当Mn2+浓度为0.03 g/L时,发酵过程中生成的g-PGA中D-谷氨酸比例不变,维持在75%左右.

关键词: g-聚谷氨酸, 立体异构, 谷氨酸消旋酶, Mn2+

Abstract: The stereochemical composition of poly-g-glutamic acid (g-PGA) and glutamate racemase activity in Bacillus subtilis NX-2 were modulated by variation of Mn2+ concentration in the culture medium. As the concentration of Mn2+ varied from 0 to 0.09 g/L, the proportion of D-glutamic acid increased gradually from 18% to 77%, which was different from other g-PGA producers in species of B. subtilis ever reported, and the glutamate racemase activity increased from 0.200 to 0.441 U/mg, while the D-amino acid aminotransferase changed a little, suggesting that glutamate racemase was involved in D-glutamic acid supply and different Mn2+ concentrations could change stereochemical composition of g-PGA by regulating glutamate racemase activity. When Mn2+ concentration was 0.03 g/L, the proportion of D-glutamic acid remained constant throughout cultivation, approximately 75%, this was different from B. subtilis F-2-01, the stereochemical composition of g-PGA produced by the microorganism changed during cultivation. Key words: poly-g-glutamic acid; stereochemical composition; glutamate racemase; Mn2+

Key words: poly-g-glutamic acid, stereochemical composition, glutamate racemase, Mn2+