LABELING OF PROTEINS WITH C-11 IN HIGH SPECIFIC RADIOACTIVITY - [C-11] ALBUMIN AND [C-11] TRANSFERRIN

A method for the C-11-labelling of proteins for use in positron emission tomography is presented. Human iron-free transferrin and human serum albumin were treated with [C-11]cyanogen bromide of high specific radioactivity under physiological conditions to give the labelled proteins in high radiochemical yields using a simple and rapid procedure. In a typical experiment, 2.0 GBq of [C-11]albumin was obtained in 28-32 min synthesis time counted from the end of bombardment. The radiochemical purity was in all cases >98% and the specific radioactivity varied with the amount of protein between 10.7-141 GBq mu mol(-1) (0.3-3.8 Ci mu mol(-1)). The radiochemical yield of labelled product as a function of PH and protein concentration was studied. The labelled products were characterized using both high performance liquid chromatography and high performance capillary electrophoresis with u.v.- and radiodetection in series.