Tritiuh‐labelling in two phenylalanine residues of norleucine11‐substance P

Norleucine11-substance P and 4-chlorophenylalanine 7.8-Norleucine11- substance P were synthesized by fragment condensation. Phe/3H/7.8-norleu-cine11 -substance P was obtained by catalytic tritiation of the precursor peptide with a specific radioactivity of 27 Ci/mmole and full biological activity.