Metallo-carbonyl complexes based on the CpFe(CO)2(η1-N-imidato) system as protein labelling reagents: reactivity and selectivity studies using bovine serum albumin as a model protein

Abstract

Transition metallo-carbonyl complexes are useful bioprobes to study molecular recognition processes such as ligand-receptor interactions, owing to their intense absorption bands in the mid-IR spectral range, which enable their detection at the picomole level with FT-IR spectrometers. New chemical methods for the introduction of cyclopentadienyl iron dicarbonyl fragments into proteins have been developed. Synthesis of a maleimide and of an N-succiminidyl ester and their reactivity with a model protein, namely bovine serum albumin (BSA), are described here. Results show that BSA can be labelled by both reagents at neutral to basic pH, and, as for the maleimide, side-chain selectivity can be tuned as a function of experimental coupling conditions.