Highly Reactive and Tracelessly Cleavable Cysteine-Specific Modification of Proteins via 4-Substituted Cyclopentenone.

A rapid and cysteine-specific modification of proteins using 4-substituted cyclopentenone via a Michael addition tandem elimination reaction was developed. Compared to the classical method, this reaction featured fast kinetics with a stable product. More importantly, this conjugation could be tracelessly removed by exchange with a Michael addition donor. The conjugation and regeneration process not only exhibited little change to the structures or conformations of the proteins but also exhibited little disturbance to their biological functions, such as their enzymatic activities.