comparative analysis on the key enzymes of the glycerol cycle metabolic pathway in dunaliella salina under osmotic stresses比较分析甘油循环代谢途径的关键酶在杜氏渗透压力.pdfVIP

Comparative Analysis on the Key Enzymes of the Glycerol Cycle Metabolic Pathway in Dunaliella salina under Osmotic Stresses 1,2 3 1 Hui Chen , Yan Lu , Jian-Guo Jiang * 1 College of Food Bioengineering, South China University of Technology, Guangzhou, China, 2 Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China, 3 School of Biological Science and Engineering, South China University of Technology, Guangzhou, China Abstract The glycerol metabolic pathway is a special cycle way; glycerol-3-phosphate dehydrogenase (G3pdh), glycerol-3-phosphate phosphatase (G3pp), dihydroxyacetone reductase (Dhar), and dihydroxyacetone kinase (Dhak) are the key enzymes around the pathway. Glycerol is an important osmolyte for Dunaliella salina to resist osmotic stress. In this study, comparative activities of the four enzymes in D. salina and their activity changes under various salt stresses were investigated, from which glycerol metabolic flow direction in the glycerol metabolic pathway was estimated. Results showed that the salinity changes had different effects on the enzymes activities. NaCl could stimulate the activities of all the four enzymes in various degrees when D. salina was grown under continuous salt stress. When treated by hyperosmotic or hypoosmotic shock, only the activity of G3pdh in D. salina was significantly stimulated. It was speculated that, under osmotic stresses, the emergency response of the cycle pathway in D. salina was driven by G3pdh via its response to the osmotic stress. Subsequently, with the changes of salinity, other three enzymes started to respond to osmotic stress. Dhar played a role of balancing the cycle metabolic pathway by its forward and backward reactions. Through synergy, the four enzymes worked together for the effective flow of the cycle metabo