Kao O H, Berns D S, Town W R
Biochem J. 1973 Jan;131(1):39-50. doi: 10.1042/bj1310039.
C-Phycocyanin was isolated and purified from a uni-algal culture of an extremely halo-tolerant blue-green alga, Coccochloris elabens. This alga can be grown under laboratory conditions in 25% (w/v) NaCl. Purified halophile phycocyanin was characterized by amino acid analysis and the measurement of sedimentation velocity, fluorescence polarization and immunodiffusion as a function of protein concentration, pH and ionic strength. The results were compared with those of studies of phycocyanin isolated from Plectonema calothricoides and from several other sources. The states of aggregation previously characterized as being present in other C-phycocyanins, monomer, trimer and hexamer, were present in halophile phycocyanin and were characterized as antigenically related to all C-phycocyanins tested. The equilibrium between 3S monomer and 11S hexamer at low concentrations in halophile phycocyanin was quantitatively similar to that for other phycocyanins. The effect of pH and ionic strength on the 6S (trimer) and 11S (hexamer) aggregation of halophile phycocyanin was markedly salt-dependent and the relative amount of each aggregate in the presence of 2m-NaCl was like that of C-phycocyanin from mesophiles, in the absence of additional salt. In antigenic relationship and aggregation properties, the phycocyanin from C. elabens appeared to be most closely related to that isolated from the thermophilic blue-green alga, Synechococcus lividus. Amino acid content of the halophile phycocyanin indicated the presence of a significantly larger number of acidic residues than that found in mesophiles. Explanations of the properties of the halophile protein require consideration of a strong contribution of hydrophobic forces and utilize both charge-shielding and salting-out effects.
从一种极端耐盐的蓝藻——纤细球藻的单藻培养物中分离并纯化了C-藻蓝蛋白。这种藻类能够在实验室条件下于25%（w/v）的氯化钠溶液中生长。通过氨基酸分析以及沉降速度、荧光偏振和免疫扩散随蛋白质浓度、pH值和离子强度变化的测量，对纯化后的嗜盐藻蓝蛋白进行了表征。将结果与从丝状鞘丝藻及其他几种来源分离得到的藻蓝蛋白的研究结果进行了比较。嗜盐藻蓝蛋白中存在先前在其他C-藻蓝蛋白中所表征的聚集状态，即单体、三聚体和六聚体，并且被表征为与所有测试的C-藻蓝蛋白具有抗原相关性。嗜盐藻蓝蛋白在低浓度下3S单体和11S六聚体之间的平衡在数量上与其他藻蓝蛋白相似。pH值和离子强度对嗜盐藻蓝蛋白6S（三聚体）和11S（六聚体）聚集的影响明显依赖于盐，在2m - NaCl存在下每种聚集体的相对量与在没有额外盐的情况下嗜温菌的C-藻蓝蛋白相似。在抗原关系和聚集特性方面，纤细球藻的藻蓝蛋白似乎与从嗜热蓝藻——活泼聚球藻中分离得到的藻蓝蛋白关系最为密切。嗜盐藻蓝蛋白的氨基酸含量表明其酸性残基的数量明显多于嗜温菌中的藻蓝蛋白。对嗜盐蛋白特性的解释需要考虑疏水力的强大作用，并利用电荷屏蔽和盐析效应。
