小球藻RubisCO的纯化及其在异养向自养转变过程中的含量变化

Purification of RubisCO from Chlorella Chlorella protothecoides and Its Content Change During Transition fromHetertrophy to Autotrophy

经硫酸铵分部沉淀、ＳｅｐｈａｃｒｙｌＳ－３００和ＤＥＡＥ－纤维素柱层析纯化了小球藻ＲｕｂｉｓＣＯ，得率为１５％，比活力达１．２３２μｍｏｌＣＯ２ｍｓ－１ｍｉｎ－１，分子量是５００ｋＤ，它和菠菜叶片ＲｕｂｉｓＣＯ在分子量、亚基组成和免疫特性等方面相似，反映ＲｕｂｉｓＣＯ在高等和低等植物中有较高的同源性。自养小球藻ＲｕｂｉｓＣＯ占细胞可溶性蛋白质的２４％。而异养转变后的小球藻细胞内不含ＲｕｂｉｓＣＯ。异养小球藻向自养生长转变过程中，２０ｈ后细胞内叶绿素含量逐渐增加，２４ｈ时细胞内出现ＲｕｂｉｓＣＯ，２４ｈ后大量增加，至４１ｈ时含量达最高峰；标志着小球藻细胞光合作用能力的恢复和加强。

The RubisCO (E. C. 4. 1. 1. 39)from Chlorella protothecoides was purified(Table 1 and Fig. 3) by ammoniumsulfate fractionation and column chromatography on Sephacryl S-300 (Fig.1) and DEAE-cellulose (Fig. 2). The recovery was 15 %. The specific activity of the enzyme was 1. 232 μmol CO2 mg-1 protein min-1. Its molecular weight was 500 kD. The molecular weight, subunit constitution (Fig. 4)and immunoreactivity (Fig. 5) of the enzyme were similar to those from spinach leaves.The content of RubisCO in totalsoluble protein in autotrophic C. protothecoides cells was 24%. No RubisCO was found in heterotrophic C. protothecoides cells (Table 2 ). RubisCO appeared in the C. protothecoides cells 24 hafter transition from heterotrophy to autotrophy. Then it kept increasing until 41 h. Chlorophyll appeared 20 h after transition from heterotrophy to autotrophy(Fig. 6, 7).