Design and application of basic amino acids displaying enhanced hydrophobicity
Design and application of basic amino acids displaying enhanced hydrophobicity
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DOI：
10.1021/ja029892o
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发表时间：
2003-07-02
影响因子：
15
通讯作者：
Schneider, JP
中科院分区：
文献类型：
--
作者：
Kretsinger, JK;Schneider, JP
三种非编码碱性氨基酸，单-，二-和三甲基二氨基丙酸（mmdap， dmdap和tmdap），已经合成用于蛋白质设计。二氨基丙酸（clap）侧链的共价修饰增加了甲基部分的数量，从而产生了具有不同程度增强疏水性的短碱性侧链残基家族。这些残基可用于将带电/极性相互作用引入蛋白质的疏水内部或界面空间。为了证明它们的实用性，研究人员评估了这些残基促进GCN4-p1（二聚体双链螺旋线圈）的螺旋/螺旋界面形成内部盐桥的能力。研究了在16位含有mmdap、dmdap或tmdap的gcn4基肽与在相同位置含有天冬氨酸的类似肽之间通过埋盐桥介导的异二聚化。mmdap衍生的异源二聚体比相应的dap衍生的异源二聚体稳定0.5 kcal/mol。这一结果表明，在dap侧链上加入一个甲基可以稳定异二聚体折叠。这种稳定性很可能是由于折叠时产生的溶解惩罚减少以及折叠状态下范德瓦尔斯接触的增强。在dap侧链上添加三个甲基导致异源二聚体的稳定性明显低于相应的拍子衍生的异源二聚体，这表明增加的空间体积不能很好地适应于该蛋白质的内部。出乎意料的是，两个甲基的加入导致了dmdap-肽的同三聚化。所得的三聚体相对稳定（DeltaG（37°c）°= 11.8 kcal/mol），并经历了协同热展开。GCN4-p1系统举例说明了大小和疏水性的微小增量变化如何改变蛋白质的折叠偏好。一般来说，这种多功能的残基套件可以在任何蛋白质中使用，并为蛋白质化学家提供新的选择。
Three noncoding basic amino acids, mono-, di-, and trimethyldiaminopropionic acid (mmdap, dmdap, and tmdap), have been synthesized for use in protein design. Covalent modification of a diaminopropionic acid (clap) side chain with an increasing number of methyl moieties results in a family of residues displaying short basic side chains with varying degrees of enhanced hydrophobic character. These residues may be used to introduce charged/polar interactions into the confining hydrophobic interior or interfacial spaces of proteins. As a demonstration of their utility, the ability of these residues to promote interior salt bridge formation at the helix/helix interface of GCN4-p1, a dimeric two-stranded coiled coil, was assessed. Heterodimerization mediated by buried salt bridge formation between a GCN4-based peptide containing either mmdap, dmdap, or tmdap at position 16 and an analogous peptide containing aspartic acid at the same position was studied. Mmdap-derived heterodimers are 0.5 kcal/mol more stable than the corresponding dap-derived heterodimers. This result indicates that the addition of one methyl group to the dap side chain can stabilize the heterodimeric fold. The stabilization can most likely be attributed to a decrease in the desolvation penalty incurred upon folding as well as enhanced van der Waals contacts in the folded state. The addition of three methyl groups to the dap side chain results in heterodimers that are significantly less stable than the corresponding clap-derived heterodimers, suggesting that increased steric bulk is not well accommodated in the interior of this protein. Unexpectedly, the addition of two methyl groups leads to homotrimerization of the dmdap-peptide. The resulting trimer is relatively stable (DeltaG(37degreesC)degrees = 11.8 kcal/mol) and undergoes cooperative thermal unfolding. The GCN4-p1 system exemplifies how small incremental changes in size and hydrophobicity can alter the folding preferences of a protein. Generally, this versatile suite of residues can be utilized in any protein and offer new options to the protein chemist.