A two-step fluorinase enzyme mediated 18F labelling of an RGD peptide for positron emission tomography

Abstract

A two-step radiolabelling protocol of a cancer relevant cRGD peptide is described where the fluorinase enzyme is used to catalyse a transhalogenation reaction to generate [18F]-5′-fluoro-5′-deoxy-2-ethynyladenosine, [18F]FDEA, followed by a 'click' reaction to an azide tethered cRGD peptide. This protocol offers efficient radiolabelling of a biologically relevant peptide construct in water at pH 7.8, 37 °C in 2 hours, which was metabolically stable in rats and retained high affinity for αVβ3 integrin.