New isocysteine building blocks and chemoselective peptide ligation
作者:Christian Dose、Oliver Seitz
DOI:10.1039/b309235f
日期:——
Boc-, Fmoc- and Cbz-protected isocysteine building blocks were prepared by a concise three-step procedure starting from thiomalic acid. The use of Boc/Trt-protected isocysteine provided convenient access to isocysteinyl peptides that allow the chemoselective ligation of unprotected peptide fragments in water. The pH-dependency of the isocysteine-mediated ligation was compared with that of cysteine-mediated native chemical ligation.
Selective Preparation of β-Monoesters of Mercaptosuccinic Acid with Acid or Base Labile Sulfur Protecting Groups and Esters
作者:Linda M. Gustavson、David S. Jones、Jeffrey S. Nelson、Ananthachari Srinivasan
DOI:10.1080/00397919108020819
日期:1991.1
Abstract Sulfur protected mercaptosuccinic acid β-monoesters were prepared by two complimentary methods. Alkylation of enolates of hemithioacetal protected mercaptoacetic acid with t-butyl bromoacetate directly provides the base stable t-butyl esters 2a and 2b. Alternatively, protection of the α-carboxylate and thiol as an oxathiolone permits the preparation of the base labile S-acyl protected mercaptosuccinic
A Convenient Synthesis of Isocysteine from Mercaptosuccinic Acid
作者:Linda M. Gustavson、Ananthachari Srinivasan
DOI:10.1080/00397919108020820
日期:1991.1
Abstract This communication describes a convenient, two step procedure for the preparation of S-benzyl-d,1-isocysteine from mercaptosuccinic acid in 49% yield.
Single nucleotide specific detection of DNA by native chemical ligation of fluorescence labeled PNA-probes
作者:Christian Dose、Oliver Seitz
DOI:10.1016/j.bmc.2007.04.059
日期:2008.1
DNA-directed chemical ligations provide the opportunity to diagnose DNA sequences with very high sequence specificity. Fluorescent labels have been attached to reactive probes to enable the homogeneous detection of DNA and RNA. However, it has frequently been found that the attachment of fluorescent labels results in decreases of ligation fidelity. Herein we describe the development of a fluorogenic ligation reaction that provides for 10(2)-fold to perfect sequence selectivity. The reaction is based on the isocysteine-mediated native chemical PNA ligation. It is shown that DNA-induced rate accelerations of similar to 43.000-fold can be obtained through subtle variations of the ligation conditions. PNA-thioesters and isocysteine-PNA conjugates were labeled with FAM and TMR fluorophores, respectively. For gaining rapid synthetic access, a convenient on-resin labeling approach was developed. A new PNA monomer featuring an Alloc-protected lysine side chain was synthesized and coupled in solid-phase PNA synthesis. In the event of a ligation reaction the two fluorophores are brought into proximity. It is shown that fluorescence resonance energy transfer provides a positive fluorescence signal which is specific for product formation rather than for loss of starting materials. Single base mutations can be detected within minutes and with very high sequence selectivity at optimized conditions. (C) 2007 Elsevier Ltd. All rights reserved.
Controlling Intracellular Macrocyclization for the Imaging of Protease Activity
作者:Deju Ye、Gaolin Liang、Man Lung Ma、Jianghong Rao
DOI:10.1002/anie.201006140
日期:2011.3.1
ground: An intramolecular macrocyclization reaction took place highly efficiently in live cells under the control of a specific enzyme and reduction by glutathione (GSH; see picture). Macrocyclic products (represented as blue rings) synthesized in cells self‐assembled into nanoparticles aggregated and retained at the site near the enzyme location to report local proteolytic activity in live cells.