PROTEIN AND PEPTIDE LABELING WITH (CYCLOPENTADIENYL)TRICARBONYL RHENIUM AND TECHNETIUM

A method for labeling proteins and peptides with (methoxycarbonyl cycl opentadienyl)tricarbonyl rhenium and technetium is described. The prec ursors used for this labeling are conveniently produced from perrhenat e and pertechnetate, respectively, using a double ligand transfer reac tion. For labeling the lysine residues of the model protein bovine ser um albumin, the technetium methyl ester was saponified and then transf ormed into its N-hydroxysuccinimidyl ester. For the labeling of the mo del peptides leucine enkephalin, substance P, oxytocin, and the tumor imaging/therapy candidate octreotide, the rhenium methyl ester was sap onified and activated using either 1-hydoxybenzotriazole or 1-hydroxy- 7-azabenzotriazole. The activation and peptide-coupling reactions were followed using reversed-phase (Cls) HPLC and yields averaged approxim ately 70%.