固氮鱼腥藻_AnabaenaazoticaHB686_谷氨酰胺合成酶的生化特性

固氨鱼腥藻HB686谷氨酰胺合成酶(GS)具有Mg~(2 )-依赖的生物合成活性和Mn~(2 )-依赖的γ-谷氨酰基转移酶活性.生物合成活性对ATP、谷氨酸和氯化铵有较强的亲和力,其Km值分别为0.80mM、0.48mM和0.68mM.γ-谷氨酰基转移酶对谷氨酰胺和羟氨的Km值分别为2.0mM和0.9mM.作者研究了pH和温度对谷氨酰胺合成酶活性的影响,发现蛋氨酸亚砜、尿素、铵离子、天冬氨酸和甘氨酸对谷氨酰胺合成酶均表现出不同程度的抑制作用.某些金属离子对维持谷氨酰胺合成酶的稳定有一定的作用.     

从氨的合成认识氮分子化学键的稳定性和活化

先从氮分子的化学键讨论其稳定性,再从最早工业化的合成氨出发,讨论氮分子化学键活化的相关研究,意欲探索一种元素化学新的教学方法。目的在于引导学生灵活学习并运用知识去认识自然世界,提高分析问题和解决问题的能力。     

固氮酶中N2和N2O结合位的一种新的鉴定方法

采用ＧＣ和ＧＣ－ＦＴＩＲ法，研究了Ｎ２和Ｎ２Ｏ对固氮酶催化Ｃ２Ｄ２还原活性及产物二氘代乙烯的反式－／顺式－异构体比值的影响。结果表明，Ｎ２和Ｎ２Ｏ均抑制Ｃ２Ｄ２的还原作用，并引起反式／－顺式－１，２－二氘代乙烯比值的增加。     

固氮酶铁钼辅基的激光喇曼光谱和电子光谱特性

??色固氮?(A.vinclandii-230)相???分离的???基(FeMo-co),以NMF为溶剂,经Sephadex LII-20凝???析,或在20 000xg下离心30 min的上清液,不含任何的氨基?,研究了FeMo-co的?光?曼光谱和电子光谱,对FeMo-co中含有与S配基耦合的S-S配基的可能性进行了讨论。     

Synthesis and Characterization of MoFe3S4 and Mo2Fe2S4 Single Cubanes

The synthesis of multimetallic M/S clusters by the reductive coupling of dimeric building blocks appears to be of general utility. In this paper we describe the synthesis and characterization of new single cubanes with cores such as [Mo₂Fe₂S₄]²⁺ and [MoFe₃S₄]^3+,2+.     

Increased Nitrogenase Activity in Solar-Driven Biohybrids Containing Non-photosynthetic Bacteria and Conducting Polymers

A conductive polymer-based photosynthetic biohybrid is constructed to enhance biological nitrogen fixation by increasing nitrogenase activity in the non-photosynthetic bacterium Azotobacter Chroococcum (A. Chroococcum). The light-harvesting cationic poly(fluorene-alt-phenylene) (PFP) electrostatically binds to the surface of the bacteria and possesses satisfactory conductivity to facilitate electron transfer to the bacterium, promoting the nitrogen fixation pathway through redox proteins on the surface of the bacteria when under illumination. Therefore, the nitrogenase activity, hydrogen, NH₄⁺-N and L-amino acids production are increased by 260 %, 37 %, 44 %, and 47 %, respectively. The expression levels of nifD and nifK encoding molybdenum-iron (MoFe) protein and relevant nitrogen-fixing proteins are up-regulated. These photoactive conductive polymer-bacteria biohybrids provide a new method for improving the biological nitrogen fixation capability of non-photosynthetic nitrogen-fixing bacteria.