中文摘要：

古菌蛋白质SS06904是最近发现的一个全螺旋结构的、具有弱的钙离子结合活性的蛋白质．在蛋白质纯化过程中，通过凝胶过滤层析发现SS06904具有稳定的单体和双体形式．1HNMR谱表明2种形式的核心结构类似．2D 2H-15NHSQC谱表明单体和双体的结构差异主要处在连接螺旋2和3以及5和6的2个Loop链接区域，这2个Loop链接区域是形成双体的关键区域，而其他区域具有相同的结构．通过结构分析推测并搭建了一种结构域交换的SS06904双体结构模型．这种稳定的双体形式可能是调节SS06904功能的一种方式．

英文摘要：

Archaeal protein SSO6904 is a newly-discovered protein with weak calcium binding activity. Protein SSO6904 is an all-helices protein. Protein purification by gel filtration discovered both monomer and dimer forms of SSO6904. 1H NMR spectra indicated that the monomer and dimer have similar structural core. Analysis of 2D 1H-15N HSQC spectra revealed that the major structural difference between the monomer and dimer was at the two loops connecting helices 2 and 3, and helices 5 and 6, respectively. These two loops form a key structural region for constructing the dimer, while other regions of monomer and dimer have the same structures. Structural analysis proposed a domain-swapped model of the SSO6904 dimer. The domain-swapped dimer may regulate the stability and function of SSO6904.