MOLECULAR-CONFORMATION OF PORCINE AMELOGENIN IN SOLUTION - 3 FOLDING UNITS AT THE N-TERMINAL, CENTRAL, AND C-TERMINAL REGIONS
MOLECULAR-CONFORMATION OF PORCINE AMELOGENIN IN SOLUTION - 3 FOLDING UNITS AT THE N-TERMINAL, CENTRAL, AND C-TERMINAL REGIONS
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DOI：
10.1093/oxfordjournals.jbchem.a124003
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发表时间：
1993-01-01
影响因子：
2.7
通讯作者：
AOBA, T
中科院分区：
文献类型：
--
作者：
GOTO, Y;KOGURE, E;AOBA, T
圆二色性（CD）的研究，以获得更好地了解的构象的釉原蛋白，这是从发育中的仔猪釉质分离。对完整的猪牙釉原蛋白及其降解产物进行层析纯化。合成了对应于C-末端片段的25-残基肽。这些样品的CD光谱在pH 5.0-5.3下在4 - 90 ℃的温度范围内测量。最显着的发现是，完整的釉原蛋白的CD光谱占在N-末端，中央和C-末端区域的三个片段的光谱的总和，支持的假设，即整个蛋白质的结构由离散的折叠单元。此外，低角度激光光散射分析提供了证据表明，20 kDa釉原蛋白，在形成釉质组织中最丰富的细胞外基质蛋白，在pH 5.3和25 ℃下以单体形式存在。初步得出结论，N-末端区域包含β-折叠结构，而C-末端区域的光谱特征与无规卷曲构象的光谱特征相似。中心区域的构象的特征在于在203 nm处具有强的负椭圆率，尽管其性质仍有待确定。
Circular dichroism (CD) studies were conducted to gain a better insight into the conformation of amelogenins, which were isolated from developing enamel of piglets. The intact porcine amelogenin and its degraded products were purified chromatographically. The 25-residue peptide corresponding to the segment at the C-terminus was synthesized. CD spectra of these samples were measured at pH 5.0-5.3 in the temperature range between 4 and 90-degrees-C. The most remarkable finding was that the CD spectrum of the intact amelogenin was accounted for by the sum of the spectra of the three fragments at the N-terminal, central, and C-terminal regions, supporting the hypothesis that the structure of the whole protein consists of discrete folding units. Furthermore, low-angle laser light scattering analysis provided evidence that the 20 kDa amelogenin, the most abundant extracellular matrix protein in forming enamel tissue, exists in a monomeric form at pH 5.3 and 25-degrees-C. It was tentatively concluded that the N-terminal region contains beta-sheet structures, while the spectral characteristics of the C-terminal region are similar to those of a random coil conformation. The conformation of the central region was characterized by a strong negative ellipticity at 203 nm, although its nature remains to be defined.