Jaiswal Pranita, Prasanna Radha, Kashyap Ajai Kumar
Centre for Conservation and Utilization of Blue Green Algae, Indian Agricultural Research Institute, New Delhi, India.
J Plant Physiol. 2005 Oct;162(10):1087-94. doi: 10.1016/j.jplph.2005.03.006.
The activity of enzyme carbonic anhydrase (CA) was investigated in two diazotrophic cyanobacteria, Anabaena sp. (ARM 629) and Nostoc calcicola, in the presence of CO2/NaHCO3 and different inhibitors. The CA activity increased when the cells were pretreated with a high concentration of CO2/NaHCO3 and then transferred to ambient level CO2. Maximum activity of CA was observed after 8 h of incubation in light on transfer of cells from high Ci to ambient level CO2, and was low when incubated in dark. Addition of the photosynthetic inhibitor DCMU brought about a differential reduction in CA activity, depending on the carbon source (NaHCO3/CO2). CA inhibitors--ethoxyzolamide (EZ) and acetazolamide (AZ)--inhibited the enzyme activity in both the genera, but the extent of inhibition was greater in Anabaena sp. than in N. calcicola. Such a variation in extent of inhibition/stimulation of CA activity being different in the two genera reflects differences in their inherent potential and genetic background. The relevance of such cyanobacterial strains as CO2 sinks is also discussed.
在两种固氮蓝细菌——鱼腥藻（ARM 629）和地木耳中，研究了在二氧化碳/碳酸氢钠存在以及不同抑制剂作用下碳酸酐酶（CA）的活性。当细胞用高浓度的二氧化碳/碳酸氢钠预处理后再转移到环境水平的二氧化碳中时，CA活性增加。从高浓度无机碳（Ci）转移到环境水平的二氧化碳后，在光照下培养8小时后观察到CA的最大活性，而在黑暗中培养时活性较低。添加光合抑制剂敌草隆会导致CA活性根据碳源（碳酸氢钠/二氧化碳）的不同而有差异地降低。CA抑制剂——乙氧唑胺（EZ）和乙酰唑胺（AZ）——抑制了这两个属中的酶活性，但鱼腥藻属的抑制程度比地木耳属更大。两个属中CA活性抑制/刺激程度的这种差异反映了它们内在潜力和遗传背景的不同。还讨论了此类蓝细菌菌株作为二氧化碳汇的相关性。
