Dudich I V, Zav'yalov V P, Pfeil W, Gaestel M, Zav'yalova G A, Denesyuk A I, Korpela T
Institute of Immunology, Chekhov District, Moscow Region, Russia.
Biochim Biophys Acta. 1995 Dec 6;1253(2):163-8. doi: 10.1016/0167-4838(95)00135-x.
Recently, it has been shown that small heat-shock proteins (Hsp25, Hsp27) are molecular chaperones. They bind to thermally unfolded proteins and can also assist refolding of denatured proteins. Mammalian small Hsps can form oligomeric structures of about 32 subunits. Until now, no data about cooperativity and stability of the interactions between the subunits of sHsps are available. To analyze these interactions we studied mouse Hsp25 and human Hsp27 by difference adiabatic scanning microcalorimetry (DASM) and circular dichroism (CD). Here we show that, according to DASM data, the minimum cooperatively melting structure is a sHsp-dimer. CD data indicate that Hsp25 major secondary structure, the beta-pleated conformation, is resistant to acidic influence up to pH 4.5 and, at neutral pH values, to heat treatment up to 60 degrees C. The melting pattern of Hsp25/27 bears resemblance to alpha-crystallins. CD data indicate similar secondary, tertiary and quaternary structures of the proteins compared. This finding is in agreement with the revealed homology of primary structure of these proteins and their common chaperone function.
最近的研究表明，小热休克蛋白（Hsp25、Hsp27）是分子伴侣。它们能与热变性的蛋白质结合，还能协助变性蛋白质重新折叠。哺乳动物的小热休克蛋白可形成约32个亚基的寡聚结构。到目前为止，尚无关于小热休克蛋白亚基间相互作用的协同性和稳定性的数据。为了分析这些相互作用，我们采用差示绝热扫描量热法（DASM）和圆二色性（CD）对小鼠Hsp25和人Hsp27进行了研究。在此我们表明，根据DASM数据，最小的协同熔化结构是小热休克蛋白二聚体。CD数据表明，Hsp25的主要二级结构，即β折叠构象，在pH值达4.5时对酸性影响具有抗性，在中性pH值下，对高达60℃的热处理具有抗性。Hsp25/27的熔化模式与α晶状体蛋白相似。CD数据表明，所比较的蛋白质具有相似的二级、三级和四级结构。这一发现与这些蛋白质一级结构中显示的同源性及其共同的伴侣功能一致。
