A new high sensitivity 19F probe for labeling cysteine groups of proteins

A novel iodoacetamide label 4-perfluoro-tert-butyl-phenyliodoacetamide (PFP) containing nine fluorine atoms in equivalent positions has been synthesized. It provides a homogeneous 19F NMR resonance line which can be detected with high sensitivity when coupled to proteins. As an example, the sulfhydryl groups of actin have been labeled with PFP; < 100 nmol of this medium sized protein (corresponding to 2.5 mL of a 40 microM solution) can be detected easily in a single scan at 470 MHz.