4种兜兰RubisCO的分离纯化及酶学性质初步研究

采用硫酸铵沉淀、阴离子交换层析与凝胶过滤层析的方法，分离纯化得到硬叶（P. micranthum）、紫纹（P. purpurattum）、带叶（P. hirsutissimum）和亨利（P. henryanum）4种兜兰RuBisCO的大、小亚基，分子量分别为51.5~54.5kD和15~16kD. 4种兜兰RubisCO的羧化/加氧活性在pH8.0、温度30℃时最高，其活性大小顺序为硬叶兜兰紫纹兜兰亨利兜兰带叶兜兰，且紫纹兜兰、亨利兜兰的羧化/加氧活性比值相对高于硬叶兜兰、带叶兜兰；硬叶兜兰RubisCO的Km（RuBP）值最小.4种兜兰RubisCO的特性反映了其不同的生理和生境特征.

Primary Study on the Isolation and Enzymatic Properties of RubisCO from Four Species of Paphiopedilum

RubisCOs were isolated and purified from Paphiopedilum micranthum, P. purpurattum, P. hirsutissimum and P. henryanum by (NH4)2SO4 precipitation, anion exchange and gel filtration chromatography in succession. The molecular weights of their large and small subunits were 51.5~54.5kD and 15~16 kD, respectively. Their zymologic characters were further studied. The results showed that these four RubisCOs from different Paphiopedilum had the highest activity at pH 8.0 and 30℃, and the descending order of RuBPcase/oase activity was P. micranthum, P. purpurattum, P. henryanum and P. hirsutissimum, and the RuBPcase/oase activity ratio of P. purpurattum and P. henryanum were higher than that of P. micranthum and P. hirsutissimum. The Km (RuBP) value of P. Micranthums RubisCO is the lowest in these four Paphiopedilum species, which indicated that its affinity to RuBP is the highest. The physiological and habitat characteristics of the four different Paphiopedilum were reflected by properties of RubisCOs isolated from them, which provided a basis for further investigation of their photosynthetic physiology.