海生红藻多管藻中的2种R-藻红蛋白

Two R-phycoerythrins from a Marine Red Alga Polysiphonia urceolata Grev

以新鲜的海生红藻多管藻(Polysiphonia urceolataGrev)为材料,通过DEAE-52离子交换层析,Sephadex G-150和Sephacryl S-300凝胶过滤层析纯化制备了2种R-藻红蛋白(R-phycoerythrin,R-PE)PE272-1和PE377-2.两者有非常相似的光谱特性,在非变性聚丙烯酰胺凝聚电泳中均表现单一条带,其等电点分别为4.5和4.4.SDS-PAGE和变性等电聚焦分析表明,PE272-1和PE377-2具有相同的有色亚基α、β和γ,分子质量分别为17.5、19.5和34.4,α亚基和β亚基的等电点分别为5.7和5.4.但PE377-2有分子质量为60.3和57.9 kD的2条PE272-1没有的无色多肽.PE272-1和PE377-2三亚基间的比例为3α∶3β∶γ1,表明PE272-1和PE377-2主要以(αβ)3-γ-(αβ)3-γ和LR-(αβ)3-γ-(αβ)3-γ六聚体形式存在,这些结果为R-PE六聚体式构建大型红藻藻胆体"杆"结构域研究提供有价值的实验资料.

Two R-phycoerythrins（R-PE）,PE272-1 and PE377-2,are isolated and purified from the marine red alga Polysiphonia urceolata by the ion exchange chromatography on DEAE-52 and by the gel filtration chromatography on Sephadex G-150 and Sephacryl S-300.The two prepared R-PEs have very similar spectral properties and show single band both in native PAGE and in native isoelectric focusing（IEF）.Isoelectric points（pIs） of PE272-1 and PE377-2 are 4.5 and 4.4,respectively.The polypeptide analysis by SDS-PAGE and denaturing IEF demonstrates that PE272-1 and PE377-2 contain the same colored subunits 17.5 kD α,19.5kD β and 34.4kD γ,and that α and β show pI 5.7 and 5.4,respectively.But PE377-2 also has other two colorless polypeptids and of 57.9kD and 60.3 kD,which PE272-1 has not.The three subunit proportions of PE272-1and PE377-2,3α∶3β∶γ1,indicate that PE272-1 and PE377-2 mainly exist in hexameric forms of（αβ）3-γ-（αβ） 3-γ and LR-（αβ）3-γ-（αβ）3-γ.These results give worthwhile experiment data for the investigation on the rod structure domain of R-PE constructing in phycobilisomes of red macroalgae.