Diazo groups endure metabolism and enable chemoselectivity in cellulo

Area of Science:

• Chemical Biology
• Biochemistry
• Molecular Biology

Background:

• Bioorthogonal chemistry enables specific labeling of biomolecules within living systems.
• Azido-alkyne cycloaddition is a widely used bioorthogonal reaction, but limitations exist for complex labeling strategies.

Purpose of the Study:

• To introduce a stabilized diazo group as a novel reporter for chemical biology applications.
• To evaluate the utility of ManDiaz, a diazo derivative of N-acetylmannosamine, for cellular labeling and orthogonal bioorthogonal chemistry.

Main Methods:

• Synthesis of ManDiaz, a diazo derivative of N-acetylmannosamine.
• Incubation of mammalian cells with ManDiaz to assess metabolic stability and cell surface labeling.
• 1,3-dipolar cycloaddition reactions between the diazo group of ManDiaz and strained alkynes.
• Comparison of labeling efficiency and signal generation with the azido congener, ManNAz.

Main Results:

• ManDiaz demonstrated metabolic stability and successfully labeled the surface of mammalian cells.
• The diazo group of ManDiaz underwent 1,3-dipolar cycloaddition with strained alkynes, yielding a signal comparable to ManNAz.
• The chemoselectivity of diazo and alkynyl groups allowed for dual labeling, a feat not achievable with azido and alkynyl groups.
• The smaller size of the diazo group compared to the azido group offers advantages for orthogonal labeling.

Conclusions:

• A stabilized diazo group, exemplified by ManDiaz, is a viable and effective reporter for chemical biology.
• ManDiaz enables novel orthogonal labeling strategies due to its unique reactivity and smaller size.
• The diazo group expands the toolkit for complex cellular component labeling in chemical biology.