Caged O-phosphorothioyl amino acids as building blocks for Fmoc-based solid phase peptide synthesis

Area of Science:

• Organic Chemistry
• Biochemistry
• Peptide Chemistry

Background:

• Development of novel amino acid derivatives is crucial for peptide-based drug discovery and chemical biology.
• Protected amino acids with photo-cleavable protecting groups enable site-specific modification of peptides.
• Phosphorothioate analogs offer enhanced stability compared to traditional phosphate groups.

Purpose of the Study:

• To synthesize novel caged amino acid building blocks for peptide incorporation.
• To develop a photo-cleavable protecting group strategy for amino acid derivatives.
• To create hydrolysis-resistant phosphate analogs for peptide modification.

Main Methods:

• Synthesis of 1-(2-nitrophenylethyl) caged O-phosphorothioylserine, -threonine, and -tyrosine derivatives.
• Incorporation of these derivatives into peptides using Fmoc-based solid phase synthesis.
• Utilizing pentafluorophenyl esters or symmetric anhydrides for peptide coupling.
• Photochemical deprotection using UV light to reveal the thiophosphate group.

Main Results:

• Successful synthesis of novel caged amino acid derivatives.
• Demonstrated direct incorporation of these building blocks into peptides via solid-phase synthesis.
• Confirmed photo-cleavage of the 1-(2-nitrophenylethyl) group upon UV irradiation.
• Revealed a hydrolysis-resistant thiophosphate group after deprotection.

Conclusions:

• The synthesized caged amino acids are valuable building blocks for peptide chemistry.
• The developed photo-cleavable strategy allows for controlled release of thiophosphate groups in peptides.
• These derivatives offer a route to novel peptide conjugates with enhanced stability.