X-RAY-ANALYSIS (1.4-A RESOLUTION) OF AVIAN PANCREATIC-POLYPEPTIDE - SMALL GLOBULAR PROTEIN HORMONE
X-RAY-ANALYSIS (1.4-A RESOLUTION) OF AVIAN PANCREATIC-POLYPEPTIDE - SMALL GLOBULAR PROTEIN HORMONE
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DOI：
10.1073/pnas.78.7.4175
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发表时间：
1981-01-01
期刊：
影响因子：
--
通讯作者：
WU, CW
中科院分区：
文献类型：
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作者：
BLUNDELL, TL;PITTS, JE;WU, CW
用单同晶置换和反常散射法测定了禽[火鸡]胰多肽（aPP）的晶体结构。分辨率相位延长至1.4-. ANG。通过使用修改的切线公式的分辨率。该分子含有二级结构的2个区域，即延伸的聚脯氨酸样螺旋（残基1-8）和α-聚脯氨酸样螺旋（残基1- 8）。螺旋（残基14-31），其大致反向平行。这些区域的非极性基团堆积在一起，使分子具有疏水核，尽管其尺寸很小。aPP分子在晶体中形成对称的二聚体，该晶体主要通过来自α-环的非极性基团的互锁而稳定化。螺旋aPP二聚体通过Zn 2+的配位交联; 3个aPP分子为每个Zn贡献配体。配位几何构型为畸变三角双锥。溶液中aPP分子的性质与基于晶体结构的预期一致。aPP分子具有与胰腺激素胰岛素和胰高血糖素共同的几个一般特征。所有这三种激素都有复杂的自我关联机制。与胰岛素一样，aPP似乎具有稳定的单体结构，但其生物活性似乎取决于与胰高血糖素的柔性NH 2末端区域类似的更柔性的COOH末端区域。
The crystal structure of avian [turkey] pancreatic polypeptide (aPP), a 36-residue polypeptide with some hormonal properties, was determined by using single isomorphous replacement and anomalous scattering to 2.1-.ANG. resolution. The phases were extended to 1.4-.ANG. resolution by using a modified tangent formula. The molecule contains 2 regions of secondary structure.sbd.an extended polyproline-like helix (residues 1-8) and an .alpha.-helix (residues 14-31).sbd.that run roughly antiparallel. The packing together of nonpolar groups from these regions gives the molecule a hydrophobic core in spite of its small size. The aPP molecules form a symmetrical dimer in the crystal stabilized principally by interlocking of nonpolar groups from the .alpha.-helices. The aPP dimers are crosslinked by coordination of Zn2+; 3 aPP molecules contribute ligans to each Zn. The coordination geometry is a distorted trigonal bipyramid. The properties of the aPP molecule in solution are consistent with expectations based on the crystal structure. The aPP molecule has several general features in common with the pancreatic hormones insulin and glucagon. All 3 hormones have complex mechanisms for self-association. Like insulin, aPP seems to have a stable monomeric structure but its biological activity seems to depend on the more flexible COOH-terminal region analogous to the flexible NH2-terminal region of glucagon.