不同培养条件下莱茵衣藻细胞中SGAT酶活性的变化

利用模式单细胞植物莱茵衣藻,研究不同培养条件下细胞中丝氨酸：乙醛酸氨基转移酶活性的变化情况。结果表明：莱茵衣藻SGAT酶活性的最适pH介于5￣7之间,当pH高于7以后,酶活性逐渐下降;随着细胞密度增加,SGAT酶活性降低;光强可显著影响SGAT酶活性,在一定光强范围内,随着光照强度的增加,酶活性增强;乙酸作为莱茵衣藻的唯一异养碳源也会影响SGAT酶活性,两者间呈正相关;提高氧浓度,显著地提高了细胞内SGAT的酶活性;当二氧化碳浓度增加时,细胞内SGAT的酶活性也略有升高;40℃高温和15℃低温处理后,SGAT酶活性均降低。此外,提高氧浓度时细胞内Gly含量增加,Ser含量减少,Gly/Ser的比值从0.79提高到1.49。

Variations in SGAT Enzyme Activity of Chlamydomonas reinhardtii L. Cells under Different Cultural Conditions

In this study, the model single cell plant Chlamydomonas reinhardtii was used to investigate varia- tions in serine： glyoxylate aminotransferase activity in cells under different cultural conditions. The results showed the optimum pH of SGAT was in the range of 5–7, and SGAT decreased gradually when the pH was higher than 7. SGAT activity in the cell also declined with the increase of cell density. SGAT activity was influenced significantly by the light intensity, and the effect strengthened with the increase of light intensity. Moreover, acetate, which was the sole carbon source of C. reinhardtii in heterotrophic growth, also affected the SGAT activity. In addition, SGAT activity in the cell increased remarkably when the oxygen concentration was higher than that in the normal air, and the increased carbon dioxide concentration treatment also led to an increase. The SGAT activity both reduced under 40 or 15 ℃. Furthermore, the content of Gly was increased and the content of Ser was decreased when the oxygen pressure increased in the air, resulting in a raise in Gly/ Ser ratio from 0.79 to 1.49.