Chen Z, Xu P, Barbier J R, Willick G, Ni F
Biomolecular NMR Laboratory and the Montréal Joint Centre for Structural Biology, Biotechnology Research Institute, National Research Council of Canada, Montréal, Québec, Canada.
Biochemistry. 2000 Oct 24;39(42):12766-77. doi: 10.1021/bi000882e.
The solution conformations of a selectively osteogenic 1-31 fragment of the human parathyroid hormone (hPTH), hPTH(1-31)NH(2), have been characterized by use of very high field NMR spectroscopy at 800 MHz. The combination of the CalphaH proton and (13)Calpha chemical shifts, (3)J(NH)(alpha) coupling constants, NH proton temperature coefficients, and backbone NOEs reveals that the hPTH(1-31)NH(2) peptide has well-formed helical structures localized in two distinct segments of the polypeptide backbone. There are also many characteristic NOEs defining specific side-chain/backbone and side-chain/side-chain contacts within both helical structures. The solution structure of hPTH(1-31)NH(2) contains a short N-terminal helical segment for residues 3-11, including the helix capping residues 3 and 11 and a long C-terminal helix for residues 16-30. The two helical structures are reinforced by well-defined capping motifs and side-chain packing interactions within and at both ends of these helices. On one face of the C-terminal helix, there are side-chain pairs of Glu22-Arg25, Glu22-Lys26, and Arg25-Gln29 that can form ion-pair and/or hydrogen bonding interactions. On the opposite face of this helix, there are characteristic hydrophobic interactions involving the aromatic side chain of Trp23 packing against the aliphatic side chains of Leu15, Leu24, Lys27, and Leu28. There is also a linear array of hydrophobic residues from Val2, to Leu7, to Leu11 and continuing on to residues His14 and Leu15 in the hinge region and to Trp23 in the C-terminal helix. Capping and hydrophobic interactions at the end of the N-terminal and at the beginning of the C-terminal helix appear to consolidate the helical structures into a V-shaped overall conformation for at least the folded population of the hPTH(1-31)NH(2) peptide. Stabilization of well-folded conformations in this linear 1-31 peptide fragment and possibly other analogues of human PTH may have a significant impact on the biological activities of the PTH peptides in general and specifically for the osteogenic/anabolic activities of bone-building PTH analogues.
利用800兆赫的超高场核磁共振波谱对人甲状旁腺激素（hPTH）具有选择性成骨作用的1 - 31片段hPTH(1 - 31)NH₂的溶液构象进行了表征。α-氢质子和¹³Cα化学位移、³J(NH)α耦合常数、NH质子温度系数以及主链核Overhauser效应（NOE）的综合结果表明，hPTH(1 - 31)NH₂肽在多肽主链的两个不同区域具有结构良好的螺旋结构。在这两个螺旋结构中，还有许多特征性的NOE，它们定义了特定的侧链/主链以及侧链/侧链之间的接触。hPTH(1 - 31)NH₂的溶液结构包含一个针对残基3 - 11的短N端螺旋片段，包括螺旋封端残基3和11，以及一个针对残基16 - 30的长C端螺旋。这两个螺旋结构通过明确的封端基序以及这些螺旋内部和两端的侧链堆积相互作用得到加强。在C端螺旋的一侧，存在Glu22 - Arg25、Glu22 - Lys26和Arg25 - Gln29的侧链对，它们可以形成离子对和/或氢键相互作用。在该螺旋的另一侧，存在特征性的疏水相互作用，涉及Trp23的芳香族侧链与Leu15、Leu24、Lys27和Leu28的脂肪族侧链堆积。在铰链区还存在从Val2到Leu7再到Leu11，然后延续到C端螺旋中的His14和Leu15的疏水残基线性排列。N端末端和C端螺旋起始处的封端和疏水相互作用似乎将螺旋结构整合为至少对于hPTH(1 - 31)NH₂肽折叠群体的V形整体构象。在这个线性的1 - 31肽片段以及可能的人甲状旁腺激素其他类似物中，良好折叠构象的稳定化可能对甲状旁腺激素肽的一般生物学活性，特别是对促进骨骼生长的甲状旁腺激素类似物的成骨/合成代谢活性产生重大影响。
