peptide dye conjugates fig1 b n 1 r 1 octreotate r 2 r 1 or oh the method described below is for the synthesis of octreotate cyanine dye conjugates similar procedures were used for the synthesis of other peptide dye conjugates octreotate was prepared as described in example 3 but the peptide was not cleaved from the solid support and the n terminal fmoc group of phe was retained the thiol group was cyclized with thallium trifluoroacetate and phe was deprotected to liberate the free amine bisethylcarboxymethylindocyanine dye 53 mg 75 u03bcmoles was added to an activation reagent consisting of a mixture 0 2 m hbtu hobt in dmso 375 u03bcl and 0 2 m diisopropylethylamine in dmso 375 u03bcl the activation was complete in about 30 minutes the resin bound peptide 25 u03bcmoles was then added to the dye the coupling reaction was carried out at ambient temperature for 3 hours the mixture was filtered and the solid residue was washed with dmf acetonitrile and thf after drying the green residue the peptide was cleaved from the resin and the side chain protecting groups were removed with a mixture of trifluoroacetic acid water thioanisole phenol 85 5 5 5 v v the resin was filtered and cold t butyl methyl ether mtbe was used to precipitate the dye peptide conjugate the conjugate was dissolved in acetonitrile water 2 3 v v and lyophilized the product was purified by hplc to.