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Updated: Mar 14, 2026

Efficient and Site-specific Antibody Labeling by Strain-promoted Azide-alkyne Cycloaddition
Published on: December 23, 2016
Strain-promoted azide-alkyne cycloaddition for protein-protein coupling in the formation of a bis-hemoglobin as a
Serena Singh1, Ina S Dubinsky-Davidchik1, Ronald Kluger1
1Davenport Chemical Laboratories, Department of Chemistry, University of Toronto, Toronto, Ontario, Canada M5S 3H6. r.kluger@utoronto.ca.
Abstract:
Conventional chemical approaches to protein-protein coupling present challenges due to the intrinsic competition between the desired interactions of reagents with groups of the protein as well as reactions with water. Biorthogonal Cu(i)-catalyzed azide-alkyne cycloaddition (CuAAC)-processes provide a basis to direct reactivity without functional group interference. However, the requirement for Cu(i) in CuAAC leads to complications that result from the metal ion's interactions with the protein. In principle, a similar but metal-free alternative approach to coupling could employ the reaction of an alkyne that is strained in combination with an azide (strain-promoted azide-alkyne cycloaddition, SPAAC). The method is exemplified by the combination of a cyclooctyne derivative of hemoglobin with an azide-modified hemoglobin. The bis-hemoglobin tetramer that is produced has properties consistent with those sought for use as a hemoglobin-based oxygen carrier (HBOC).
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