Features of Auxiliaries That Enable Native Chemical Ligation beyond Glycine and Cleavage via Radical Fragmentation.

Native chemical ligation (NCL) is an invaluable tool in the total chemical synthesis of proteins. Ligation auxiliaries overcome the requirement for cysteine. However, the reported auxiliaries remained limited to glycine-containing ligation sites and the acidic conditions applied for cleavage of the typically applied N-benzyl-type linkages promote side reactions.

Native chemical ligation at a base-labile 4-mercaptobutyrate N(α)-auxiliary.

Native chemical ligation (NCL) proceeds via a S-N acyl shift and, therefore, requires N-terminal cysteine. N(α)-auxiliaries have long been used to enable NCL beyond cysteine. However, the reversibility of the S-N acyl shift under the acidic conditions used to remove the commonly applied N-benzyl auxiliaries limits the scope of this reaction.

A Type of Auxiliary for Native Chemical Peptide Ligation beyond Cysteine and Glycine Junctions.

Native chemical ligation enables the chemical synthesis of proteins. Previously, thiol-containing auxiliary groups have been used to extend the reaction scope beyond N-terminal cysteine residues. However, the N-benzyl-type auxiliaries used so far result in rather low reaction rates.

Brightness through local constraint--LNA-enhanced FIT hybridization probes for in vivo ribonucleotide particle tracking.

Imaging the dynamics of RNA in living cells is usually performed by means of transgenic approaches that require modification of RNA targets and cells. Fluorogenic hybridization probes would also allow the analysis of wild-type organisms. We developed nuclease-resistant DNA forced intercalation (FIT) probes that combine the high enhancement of fluorescence upon hybridization with the high brightness required to allow tracking of individual ribonucleotide particles (RNPs).