粘球藻(Gloeocapsa sp.)细胞粗提物放氢特性研究

STUDIES ON CHARACTERISTICS OF HYDROGEN EVOLUTION BY CELL-FREE PREPARATION FROM GLOEOCAPSA SP.

粘球藻培养物细胞破碎后,经一段时间的厌氧保温处理,可诱导出较高的氢酶放氢活性。在常温厌氧条件下放置数日后,这种酶粗制剂仍可利用连二亚硫酸钠/甲基紫精作为电子供体放氢。内源电子供体放氢活性的高低与细胞破碎前内部光合产物积累水平有关,前期的暗饥饿可明显降低这种放氢,细胞破碎前后外加糖源均可提高放氢。酶反应最适温度为55℃,最适pH在6.5左右,不依赖于光,受CO、O_2和C_2H_2的抑制。这种氢酶放氧活性的诱导出现受蛋白合成抑制剂的阻止。

Hydrogenase activity was induced in the call-free preparation from unicellular blue-green alga Gloeocapsa sp. after several hour anaerobic treatment. It has been found that hydrogen evolution of the preparation may be supported by artificial electron donor sodium dithionide and added sugars besides the natural electron donars existed in the cell-free extract. The sugars added may be used as the metabolic substrates by some respiratory enzymes existed in the cell-free extract and then transformed into donors for the hydrogenase. Preillumination on the algal cultures before cell broken might accumulate photosyn thetic products and support higher late hydrogen evolution activity. And pre- vious dark-starVation obviously declined the late hydrogen evolution activity that depended on natural donor source.The hydrogen evolution activity was inhibited by CO, O_2 and C_2H_2.The inducibl, hydrogenase of the alga showed rather stable for days under conditions of anaerobic and different temperature, 25℃ and 4℃. The optimal temperature and pH for the reaction were about 55℃ and pH6.5 respectively.The induction of the hydrogenase activity was almost absolutly repressed by some antibiotics inhibiting protein synthesis of microorganisms, such as chloramphenicol, strepto aycin and tetracyclin; But the antibiotics did not show obvious inhibition to the induced hydrogen evolution activity. It is unclear whether hydrogenase was synthesized in vitro.