Retention of the cis proline conformation in tripeptide fragments of bovine pancreatic ribonuclease A containing a non-natural proline analogue, 5,5-dimethylproline
Retention of the cis proline conformation in tripeptide fragments of bovine pancreatic ribonuclease A containing a non-natural proline analogue, 5,5-dimethylproline
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DOI：
10.1021/ja9930317
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发表时间：
1999-12-15
影响因子：
15
通讯作者：
Scheraga, HA
中科院分区：
文献类型：
--
作者：
An, SSA;Lester, CC;Scheraga, HA
人们的注意力集中在 L-5,5-二甲基脯氨酸 (dmP) 作为替代品，以将 L-脯氨酸 (Pro) 锁定在肽和蛋白质中的顺式构象中，以防止具有顺式 X-Pro 肽基团的蛋白质展开时发生顺/反异构化。已开发出获得光学纯的 L-dmP 并将该空间位阻残基作为三肽中中心残基的程序，该三肽适合片段偶联以制备合成蛋白质。基于牛胰腺核糖核酸酶 A (RNase A) 中残基 92-94 (Tyr-Pro-Asn:YPN) 和 113-115 (Asn-Pro-Tyr: NPY) 的序列，其中 X-Pro 肽基团呈顺式构象，三肽 Ac-Tyr-dmP-Asn (YdmPN) 和 Ac-Asn-dmP-Tyr (NdmPY) 被合成，并通过 2D H-1 核磁共振 (NMR) 光谱确定了它们的结构。发现YdmPN在6至60℃之间仅以顺式构象存在，而NdmPY被发现具有一些反式组分，当温度在6至80℃范围内增加时，反式组分从约10％增加至约21％。YdmPN和顺式-NdmPY都采用VI型反转，脯氨酸也是如此。 YdmPN 和顺式 NdmPY 的 NMR 结构与 RNase A 相应部分的 X 射线结构相当，反式 NdmPY 的 NMR 结构与分离的三肽 Ac-NPY 的 X 射线结构兼容。这些结果表明，在多种蛋白质问题中，L-dmP 是脯氨酸的有前途的替代品，可将 X-Pro 肽基团限制为顺式构象。
Attention is focused on L-5,5-dimethylproline (dmP) as a substitute to lock L-proline (Pro) in a cis conformation in peptides and proteins, to prevent cis/trans isomerization when a protein with cis X-Pro peptide groups unfolds. Procedures have been developed to obtain optically pure L-dmP and to incorporate this sterically hindered residue as tbe central one in tripeptides that are suitable for fragment coupling to prepare synthetic proteins. Based on the sequences of residues 92-94 (Tyr-Pro-Asn:YPN) and 113-115 (Asn-Pro-Tyr: NPY) in bovine pancreatic ribonuclease A (RNase A), in which the X-Pro peptide groups are in the cis conformation, the tripeptides Ac-Tyr-dmP-Asn (YdmPN) and Ac-Asn-dmP-Tyr (NdmPY) were synthesized, and their structures were determined by 2D H-1 nuclear magnetic resonance (NMR) spectroscopy. YdmPN was found to exist solely in the cis conformation between 6 and 60 degrees C, whereas NdmPY was found to have some trans component that increased from about 10% to about 21% as the temperature increased over the range between 6 and 80 degrees C. Both YdmPN and cis-NdmPY adopt a type VI reverse turn, as does proline. The NMR structures of YdmPN and cis-NdmPY are comparable with the X-ray structures of the corresponding portions of RNase A, and the NMR structure of trans-NdmPY is compatible with the X-ray structure of the isolated tripeptide, Ac-NPY. These results demonstrate that L-dmP is a promising substitute for proline in a variety of protein problems to constrain the X-Pro peptide group to the cis conformation.