Botany Department, University of Georgia, Athens, Georgia 30602.
Plant Physiol. 1986 Mar;80(3):685-91. doi: 10.1104/pp.80.3.685.
Distinctive properties are identified in the molecular structure of ribulose, 1,5-bisphosphate carboxylase/oxygenase (RuBPCase) in chlorophyll c-containing algae (i.e., chromophytes). Using purified enzyme from Cryptomonas sp., Coccolithophora sp., and Cylindrotheca fusiformis, we have determined that the RuBPCase holoenzyme of each species has a molecular weight, subunit composition, and isoelectric points of its subunits similar to the purified enzymes from pea and Chlamydomonas reinhardtii. The large subunits from chromophytes exhibit microheterogeneity in their isoelectric points, whereas two to four well-resolved isoelectric variants of the small subunit were observed in each RuBPCase preparation. In spite of the high degree of similarity in terms of physical properties, both the small and large RuBPCase subunits of the chromophytes are structurally different from those of chlorophytes; immunological studies demonstrate that RuBPCase subunits of these two groups have few antigenic determinants in common.
在含有叶绿素 c 的藻类（即色素体）的核酮糖 1,5-二磷酸羧化酶/加氧酶（RuBPCase）的分子结构中，确定了其具有独特的性质。我们使用来自Cryptomonas sp.、Coccolithophora sp. 和 Cylindrotheca fusiformis 的纯化酶，确定了每个物种的 RuBPCase 全酶的分子量、亚基组成和亚基的等电点与其来自豌豆和莱茵衣藻的纯化酶相似。色素体的大亚基在等电点上表现出微异质性，而在每个 RuBPCase 制剂中观察到小亚基的两到四个分辨率良好的等电变体。尽管在物理性质方面具有高度的相似性，但色素体的小和大亚基 RuBPCase 在结构上与叶绿体的不同；免疫研究表明，这两个组的 RuBPCase 亚基很少有共同的抗原决定簇。
