Fluorogenic Peptide Substrates for Serine and Threonine Phosphatases
摘要:
A new fluorescent assay for Ser/Thr protein phosphatases has been developed. Hydrolysis of a phosphoSer residue liberates the Ser hydroxyl group, which induces a cyclization reaction on the N-terminal carbamate and releases a fluorescent reporter. Sequence selectivity is observed using several peptide substrates against alkaline phosphatase (ALP), bacteriophage lambda protein phosphatase (lambda-PPase), and vaccinia H1 related phosphatase (VHR). These studies suggest that the assay could be a useful tool for profiling the substrate specificities of medicinally important phosphatases.
Selective Disruption of Early/Recycling Endosomes: Release of Disulfide-Linked Cargo Mediated by a N-Alkyl-3β-Cholesterylamine-Capped Peptide
摘要:
The use of endocytic uptake pathways to deliver poorly permeable molecules into mammalian cells is often plagued by entrapment and degradation of material in late endosomes and lysosomes. As a strategy to prevent the exposure of cargo to these highly hydrolytic membrane-sealed compartments, we synthesized derivatives of the membrane anchor N-alkyl-3 beta-cholesterylamine that selectively target linked compounds to less hydrolytic early/recycling endosomes. By targeting a pH-dependent membrane-lytic dodecapeptide and dislufide-linked flurophore to these compartments in Chinese hamster ovary cells or Jurkat lymphocytes, membranes of early-recycling endosomes were selectively disrupted, resulting in cleavage of the disulphide and escape of the fluorophore into cytosol and nucleus with low toxicity. The ability os appropriately designed N-alkyl-3 beta-cholesterylamines to deliver cargo into and release dislufide-linked cargo from relatively nonhydrolytic early/recycling endosomes may be useful for the delivery of a variety of sensitive molecules into living mammalian cells.
Indium–Silver- and Zinc–Silver-Mediated Barbier–Grignard-Type Alkylation Reactions of Imines by Using Unactivated Alkyl Halides in Aqueous Media
作者:Zhi-Liang Shen、Hao-Lun Cheong、Teck-Peng Loh
DOI:10.1002/chem.200701468
日期:2008.2.18
efficient and practical method for the Barbier-Grignard-typealkylationreactions of simple imines by using a one-pot condensation of various aldehydes, amines (including the aliphatic and chiral version), and secondary alkyl iodides has been developed. The reaction proceeded more efficiently in water than in organic solvents. Without the use of CuI, it mainly gave the imine self-reductive coupling product
Indium (Zinc)−Copper-Mediated Barbier-Type Alkylation Reaction of Nitrones in Water: Synthesis of Amines and Hydroxylamines
作者:Yong-Sheng Yang、Zhi-Liang Shen、Teck-Peng Loh
DOI:10.1021/ol8027362
日期:2009.3.19
An efficient method for the Barbier-type alkylation reaction of various nitrones (including chiral version) and alkyl halides in water is described. The amines and hydroxylamines can be obtained in good yields, depending on the judicious choice of the metal complexes used.