Fluorinated proteins as potential 19F magnetic resonance imaging and spectroscopy agents.

Fluorinated proteins have been synthesized and characterized as potential in vivo 19F magnetic resonance imaging (MRI) and spectroscopy (MRS) agents. Proteins labeled with fluorine include bovine serum albumin, gamma-globulin, and purified immunoglobulin (IgG). The amino groups in proteins were selectively trifluoroacetylated using S-ethyl trifluorothioacetate to synthesize fluorinated proteins (TFA-protein; 1-3). In another approach, trifluoroacetamidosuccinic anhydride has been used to prepare corresponding fluorinated derivatives of proteins (TFASA-protein; 4-6). The fluorinated proteins have been purified by exhaustive dialysis and isolated in good yields (55-76%). The fluorinated proteins exhibit useful NMR characteristics and the biocompatibility for in vivo studies. The initial investigations demonstrate the potential of these new fluorinated proteins as in vivo MRI/MRS probes.