4-Benchrotrenyl Pyrylium Salts as Protein Organometallic Labelling Reagents

Pyrylium ions are useful reagents to selectively modify the amino group of protein lysine residues. This property was exploited here to label proteins with chromium tricarbonyl complexes in the form of 4-benchrotrenyl pyridinium ions. Kinetic studies of the reaction of a series of benchrotrenyl pyrylium salts with water and n-butylamine were performed and revealed that the overall reactivity of these compounds was highly dependent on their substitution pattern. These compounds could find application in protein X-ray crystallography.