Pan O H, Beck K
Department of Biological Science, Rutgers-The State University of New Jersey, Piscataway, New Jersey 08855, USA.
J Biol Chem. 1998 Jun 5;273(23):14205-9. doi: 10.1074/jbc.273.23.14205.
Matrilin-2 is a member of von Willebrand factor A containing extracellular matrix proteins in which the cDNA-derived sequence shows similar domain organization to cartilage matrix protein/matrilin-1, but information on the protein structure is limited. Here we studied the oligomerization potential of a synthetic peptide NH2-ENLILFQNVANEEVRKLTQRLEEMTQRMEALENRLKYR-COOH corresponding to the C-terminal sequence of mouse matrilin-2. The central portion of this sequence shows a periodicity of hydrophobic residues occupying positions a and d of a heptad pattern (abcdefg)n, which is characteristic for alpha-helical coiled-coil proteins. Circular dichroism spectroscopy revealed a high alpha-helical content, and the shape of the spectra is indicative for a coiled-coil conformation. Chemical cross-linking and size exclusion chromatography suggest a homotrimeric configuration. Thermal denaturation in benign buffer shows a single cooperative transition with DeltaH0 = -375 kJ/mol. Melting temperatures Tm varied from 38 to 51 degreesC within a concentration range of 10 to 85 microM, which is about 35 degreesC lower than determined for a peptide corresponding to the C-terminal domain of matrilin-1. The data suggest that despite the low sequence identity within this region, matrilin-2 will form a homotrimer as matrilin-1 does.
基质金属蛋白酶-2是含有细胞外基质蛋白的血管性血友病因子A成员，其cDNA衍生序列显示出与软骨基质蛋白/基质金属蛋白酶-1相似的结构域组织，但关于该蛋白质结构的信息有限。在这里，我们研究了与小鼠基质金属蛋白酶-2 C末端序列相对应的合成肽NH2-ENLILFQNVANEEVRKLTQRLEEMTQRMEALENRLKYR-COOH的寡聚化潜力。该序列的中央部分显示出疏水残基的周期性，占据七肽模式（abcdefg）n的a和d位置，这是α-螺旋卷曲螺旋蛋白的特征。圆二色光谱显示高α-螺旋含量，光谱形状表明为卷曲螺旋构象。化学交联和尺寸排阻色谱表明为同三聚体构型。在良性缓冲液中的热变性显示出单一的协同转变，ΔH0 = -375 kJ/mol。在10至85 microM的浓度范围内，熔解温度Tm在38至51℃之间变化，这比与基质金属蛋白酶-1 C末端结构域相对应的肽所确定的温度低约35℃。数据表明，尽管该区域内的序列同一性较低，但基质金属蛋白酶-2将像基质金属蛋白酶-1一样形成同三聚体。
