Native Chemical Ligation of Thioamide-Containing Peptides: Development and Application to the Synthesis of Labeled α-Synuclein for Misfolding Studies
作者:Solongo Batjargal、Yanxin J. Wang、Jacob M. Goldberg、Rebecca F. Wissner、E. James Petersson
DOI:10.1021/ja2113245
日期:2012.6.6
Thioamide modifications of the peptide backbone are used to perturb secondary structure, to inhibit proteolysis, as photoswitches, and as spectroscopic labels. Thus far, their incorporation has been confined to single peptides synthesized on solid phase. We have generated thioamides in C-terminal thioesters or N-terminal Cys fragments and examined their compatibility with native chemical ligation conditions
肽主链的硫代酰胺修饰用于扰乱二级结构、抑制蛋白水解、作为光开关和光谱标记。到目前为止,它们的掺入仅限于固相合成的单一肽。我们在 C 端硫酯或 N 端 Cys 片段中生成了硫代酰胺,并检查了它们与天然化学连接条件的相容性。大多数序列变体可以与 TCEP 或 DTT 作为还原剂以良好的产率偶联,但在延长 TCEP 孵育时观察到一些副产物。此外,我们发现硫代酰胺与 N 末端 Cys 的噻唑烷保护相容,因此可以使用多重连接来构建更大的蛋白质。由于硫代酰胺的酸不稳定性阻碍了使用 Boc 化学在树脂上合成硫酯,因此我们设计了一种合成硫代酰胺肽的方法,该方法具有原位显示的掩蔽 C 末端硫酯。最后,我们证明,通过合成用于蛋白质折叠研究的淀粉样蛋白 α-突触核蛋白的标记版本,硫代酰胺肽可以与表达的蛋白质片段偶联,生成带有主链硫代酰胺标记的大蛋白质。在原理验证实验中,我们证明硫代酰胺的荧光猝灭可用于跟踪标记的
Thioamide quenching of intrinsic protein fluorescence
作者:Jacob M. Goldberg、Rebecca F. Wissner、Alyssa M. Klein、E. James Petersson
DOI:10.1039/c1cc14708k
日期:——
Thioamides quench tryptophan and tyrosine fluorescence in a distance-dependent manner and thus can be used to monitor the binding of thioamide-containing peptides to proteins.
Thioamide Quenching of Fluorescent Probes through Photoinduced Electron Transfer: Mechanistic Studies and Applications
作者:Jacob M. Goldberg、Solongo Batjargal、Benson S. Chen、E. James Petersson
DOI:10.1021/ja409709x
日期:2013.12.11
expand the scope of fluorophores quenched by thioamides to include dyes suitable for microscopy and single-molecule studies, including fluorescein, Alexa Fluor 488, BODIPY FL, and rhodamine 6G. We describe the photochemistry of these systems and explore applications that demonstrate the utility of thioamide quenching of fluorescein to studying protein folding and proteolysis.
Thioamides as Fluorescence Quenching Probes: Minimalist Chromophores To Monitor Protein Dynamics
作者:Jacob M. Goldberg、Solongo Batjargal、E. James Petersson
DOI:10.1021/ja1044924
日期:2010.10.27
Decreasing the size of spectroscopic probes can afford higher-resolution structural information from fluorescence experiments. Therefore, we have developed p-cyanophenylalanine (Cnf) and backbone thioamides as a fluorophore/quencher pair. Through the examination of a series of thiopeptides, we have determined the working distance for this pair to be 8-30 A. We have also carried out a proof-of-principle protein-folding experiment in which a Cnf/thioamide-labeled version of villin headpiece HP35 was thermally unfolded while the Cnf/thioamide distance was monitored by fluorescence. For a given protein, thioamide substitutions could be used to track motions with a much greater number of measurements than for current fluorescence probes, providing a dense array of data with which to model conformational changes.
Thioamide-Based Fluorescent Protease Sensors
作者:Jacob M. Goldberg、Xing Chen、Nataline Meinhardt、Doron C. Greenbaum、E. James Petersson
DOI:10.1021/ja412297x
日期:2014.2.5
Thioamide quenchers can be paired with compact fluorophores to design "turn-on" fluorescent protease substrates. We have used this method to study a variety of serine-, cysteine-, carboxyl-, and metallo-proteases, including trypsin, chymotrypsin, pepsin, thermolysin, papain, and calpain. Since thioamides quench some fluorophores red-shifted from those naturally occurring in proteins, this technique can be used for real time monitoring of protease activity in crude preparations of virtually any protease. We demonstrate the value of this method in three model applications: (1) characterization of papain enzyme kinetics using rapid-mixing experiments, (2) selective monitoring of cleavage at a single site in a peptide with multiple proteolytic sites, and (3) analysis of the specificity of an inhibitor of calpain in cell lysates.