氧化胁迫对Alkalibacterium sp.F26防御酶和辅因子的影响(英文)  

Effects of Oxidative Challenge on Defensive Enzyme and Cofactors Level in Alkalibacterium sp. F26

作　　者：段菁菁[1] 刘立明[1] 华兆哲[1] 陈坚[1] 

机构地区：[1]江南大学工业生物技术教育部重点实验室

出　　处：《微生物学通报》2008年第9期1385-1392,共8页Microbiology China

基　　金：the Key Project of China National Programs for Fundamental Research and Develop-ment (No. 2007CB714306); National Natural Science Foundation of China (No. 20676056)

摘　　要：将一株能够高产过氧化氢酶的低度嗜盐嗜碱菌Alkalibacterium sp.F26作为模式微生物,采用高效液相色谱技术测定胞内代谢物浓度,研究氧化胁迫对其防御酶活性和辅因子的影响。研究结果表明:相比低浓度H2O2(<1mmol/L)胁迫,此菌株在高浓度H2O2(>1mmol/L)胁迫下的应答表现更为明显:经3mmol/LH2O2胁迫后胞内CAT酶活为106.54U/mgprotein,是对照产量的1.76倍;ATP浓度则从对照浓度20.55μmol/L下降到17.80μmol/L;NAD+浓度自对照样品的69.89μmol/L减少至31.77μmol/L。由于ATP和NAD+浓度的减少,相比未经过H2O2胁迫菌体,细胞能荷值EC从0.77降低至0.68,NADH/NAD+则从0.08增加至0.41。然而,这种应答机制在细胞受到低浓度H2O2的胁迫后并不明显:除发现100μmol/LH2O2能够导致细胞防御机制的激活而使胞内ATP浓度相比对照有所增加的情况外,经50μmol/L和500μmol/LH2O2胁迫后胞内ATP水平从对照的22.69μmol/L只下降到22.38μmol/L和13.70μmol/L;并且此种胁迫条件下NADH浓度变化也不显著。In this paper, a slight halophilic alkaliphile strain, Alkalibacterium sp. F26, which produced high level of intracellular CAT observed in previous research, was selected as a model microbial to explain the responses of this bacterium to oxidative stress. The results indicated that Alkalibacterium sp. F26 had obvious responses to higher concentration （〉1 mmol/L） of H2O2 than that to lower H2O2 （〈1 mmol/L） challenge from the aspects of defensive enzyme synthesis and cofactors level variation. As for catalase production, the activity increased up to 106.54 U/mg protein which was 1.76 fold of the control when cells were challenged by 3 mmol/L H2O2, but its activity only was 1.13 fold when H2O2 was 100 μmol/L. As far as energy state was concerned, ATP production and NAD^＋ generation were significantly inhibited from 20.55 μmol/L to 17.80 μmol/L and 69.89 μmol/L to 31.77 μmol/L, respectively, leading to the drop of energy charge from 0.77 to 0.68 and the increase of the portion of NADH/NAD^＋ from 0.08 to 0.41 in the former case. However, these effects were less distinct under lower concentration of H2O2. Except of the condition of 100 μmol/L H2O2, under which the activation of defensive mechanism resulted in an increase of ATP, the level of ATP dropped from 22.69 μmol/L of the control to 22.38μmol/L and 13.70μmol/L when challenged by 50μmol/L and 500 μmol/L H2O2. Besides, the concentration of NADH fluctuated and the NAD^＋ gradually reduced when H2P2 below 1 mmol/L.

关 键 词：活性氧胁迫 过氧化氢酶(CAT) ATP NADH NAD^+ 

分 类 号：Q93[生物学—微生物学]