Chemical Modification of the N Termini of Unprotected Peptides for Semisynthesis of Modified Proteins by Utilizing a Hydrophilic Protecting Group

Abstract

A simple and efficient strategy for the selective modification of the peptide N terminus with an unnatural amino acid is described. A peptide having a SUMO‐HisTag‐TEV sequence (SUMO: small ubiquitin‐related modifier, TEV: tobacco etch virus) preceding the N terminus of the target peptide was designed. Recombinant expression in E. coli and subsequent SUMO protease cleavage yielded the HisTag‐TEV‐target peptide. Partial protection of the lysine side chains of this peptide with d‐glucopyranosyloxycarbonyl and removal of the HisTag‐TEV sequence by TEV protease yielded the partially protected peptide with a free N‐terminal amine. Coupling of selenocysteine selectively at the N terminus and subsequent acidic deprotection of the carbohydrate protecting groups yielded a modified peptide that can be used for native chemical ligation (NCL). As a proof of concept, the modification of a longer recombinant peptide with selenocysteinylserine (GalNAc) at the N terminus was demonstrated.

Enhancing activity of food protein‐derived peptides: An overview of pretreatment, preparation, and modification methods

“…It can also affect the immunogenicity of peptides and proteins, as well as their pharmacokinetic and pharmacodynamic properties (Chandrashekar et al., 2021). In certain cases, the multifunctional properties of glycosylation can be leveraged to utilize carbohydrates as temporary hydrophilic side chain protecting groups for recombinant polypeptides (Chandrashekar et al., 2019). This approach can increase the solubility and physical stability of hydrophobic and aggregation‐prone polypeptides, and extend their half‐life in the bloodstream.…”

Chemical Glycosylation and Its Application to Glucose Homeostasis-Regulating Peptides

“…Glycosylation, being a natural modification, is known to improve the pharmacodynamics and pharmacokinetics profile without leading to immunogenicity (Walsh and Jefferis, 2006;Solá and Griebenow, 2010). The versatility of glycosylation has also led to the use of carbohydrates as temporary hydrophilic side chain protecting group for recombinant peptides (Chandrashekar et al, 2019). This results in an increase in the solubility and physical stability of hydrophobic and aggregation prone peptide and allows selective introduction of glycans and other non-natural modifications.…”

GEQB‐Nachwuchspreis: O. Vázquez / Whistler‐Preis für Kohlenhydratchemie: Y. Kajihara / Barry‐Cohen‐Preis: D. Rauh

“…Die aktuelle Forschung in Kajiharas Gruppe dreht sich um die Synthese von Glykoproteinen mit homogenen Human‐N‐Glykanen und die Aufklärung der Glykanfunktionen. Er publizierte ein Full Paper über die chemische N‐terminale Modifizierung ungeschützter Peptide in Chemistry—A European Journal und eine Zuschrift über die Synthese von Glc 1 Man 9 ‐Glykoprotein‐Sonden in der Angewandten Chemie …”