N-Terminal Modification of Proteins with o-Aminophenols
摘要:
The synthetic modification of proteins plays an important role in chemical biology and biomaterials science. These fields provide a constant need for chemical tools that can introduce new functionality in specific locations on protein surfaces. In this work, an oxidative strategy is demonstrated for the efficient modification of N-terminal residues on peptides and N-terminal proline residues on proteins. The strategy uses o-aminophenols or o-catechols that are oxidized to active coupling species in situ using potassium ferricyanide. Peptide screening results have revealed that many N-terminal amino acids can participate in this reaction, and that proline residues are particularly reactive. When applied to protein substrates, the reaction shows a stronger requirement for the proline group. Key advantages of the reaction include its fast second-order kinetics and ability to achieve site-selective modification in a single step using low concentrations of reagent. Although free cysteines are also modified by the coupling reaction, they can be protected through disulfide formation and then liberated after N-terminal coupling is complete. This allows access to doubly functionalized bioconjugates that can be difficult to access using other methods.
Synthesis of peptides by the solid-phase method. 7. Substance P and analogs
摘要:
Substance P and 21 related peptides containing isosteric or isofunctional groups were prepared by the solid-phase method. After purification by gel filtration and ion-exchange chromatography, the compounds were characterized by thin-layer chromatography, paper electrophoresis, and amino acid and elemental analysis. The biological activities of the peptides were evaluated in vitro on the guinea pig ileum, the rabbit mesenteric vein, and the dog common carotid artery and in vivo on the rat blood pressure. It is shown that the replacement of some residues in the undecapeptide substance P causes variable losses of apparent affinity with a little or no change in the intrinsic activity. All the analogues used in the present study were found to be inactive as antagonists.
Structure and Biosynthesis of Isatropolones, Bioactive Amine-Scavenging Fluorescent Natural Products from <i>Streptomyces</i>
Gö66
作者:Xiaofeng Cai、Yi-Ming Shi、Nicole Pöhlmann、Ole Revermann、Isabel Bahner、Sacha J. Pidot、Frank Wesche、Helmut Lackner、Claudia Büchel、Marcel Kaiser、Christian Richter、Harald Schwalbe、Timothy P. Stinear、Axel Zeeck、Helge B. Bode
DOI:10.1002/anie.201701223
日期:2017.4.24
The natural products isatropolone A–C (1–3) were reisolated from Streptomyces Gö66, with 1 and 3 showing potent activity against Leishmania donovani. They contain a rare tropolone ring derivedfrom a type II polyketide biosynthesis pathway. Their biosynthesis was elucidated by labeling experiments, analysis of the biosynthesis gene cluster, its partial heterologous expression, and structural characterization
Negative-Ion Electron Capture Dissociation: Radical-Driven Fragmentation of Charge-Increased Gaseous Peptide Anions
作者:Hyun Ju Yoo、Ning Wang、Shuyi Zhuang、Hangtian Song、Kristina Håkansson
DOI:10.1021/ja207736y
日期:2011.10.26
The generation of gaseous polyanions with a Coulomb barrier has attracted attention as exemplified by previous studies of fullerene dianions. However, this phenomenon has not been reported for biological anions. By contrast, electron attachment to multiply charged peptide and protein cations has seen a surge of interest due to the high utility for tandem mass spectrometry (MS/MS). Electron capture dissociation (ECD) and electron transfer dissociation (ETD) involve radical-driven fragmentation of charge-reduced peptide/protein cations to yield N-C-alpha backbone bond cleavage, resulting in predictable c'/Z(center dot)-type product ions without loss of labile post-translational modifications (PTMs). However, acidic peptides, e.g., with biologically important PTMs such as phosphorylation and sulfonation, are difficult to multiply charge in positive ion mode and show improved ionization in negative-ion mode. We found that peptide anions ([M - nH](n-), n >= 1) can capture electrons within a rather narrow energy range (similar to 3.5-6.5 eV), resulting in charge-increased radical intermediates that undergo dissociation analogous to that in ECD/ETD. Gas-phase zwitterionic structures appear to play an important role in this novel MS/MS technique, negative-ion electron capture dissociation (niECD).
Synthesis of peptides by the solid-phase method. 7. Substance P and analogs
Substance P and 21 related peptides containing isosteric or isofunctional groups were prepared by the solid-phase method. After purification by gel filtration and ion-exchange chromatography, the compounds were characterized by thin-layer chromatography, paper electrophoresis, and amino acid and elemental analysis. The biological activities of the peptides were evaluated in vitro on the guinea pig ileum, the rabbit mesenteric vein, and the dog common carotid artery and in vivo on the rat blood pressure. It is shown that the replacement of some residues in the undecapeptide substance P causes variable losses of apparent affinity with a little or no change in the intrinsic activity. All the analogues used in the present study were found to be inactive as antagonists.
N-Terminal Modification of Proteins with <i>o</i>-Aminophenols
作者:Allie C. Obermeyer、John B. Jarman、Matthew B. Francis
DOI:10.1021/ja500728c
日期:2014.7.9
The synthetic modification of proteins plays an important role in chemical biology and biomaterials science. These fields provide a constant need for chemical tools that can introduce new functionality in specific locations on protein surfaces. In this work, an oxidative strategy is demonstrated for the efficient modification of N-terminal residues on peptides and N-terminal proline residues on proteins. The strategy uses o-aminophenols or o-catechols that are oxidized to active coupling species in situ using potassium ferricyanide. Peptide screening results have revealed that many N-terminal amino acids can participate in this reaction, and that proline residues are particularly reactive. When applied to protein substrates, the reaction shows a stronger requirement for the proline group. Key advantages of the reaction include its fast second-order kinetics and ability to achieve site-selective modification in a single step using low concentrations of reagent. Although free cysteines are also modified by the coupling reaction, they can be protected through disulfide formation and then liberated after N-terminal coupling is complete. This allows access to doubly functionalized bioconjugates that can be difficult to access using other methods.