Synthesis and contractile activity of the C-terminal heptapeptide of substance P with N5-dimethyl glutamine in the 6-position. Active site studies

Summary The synthesis and testing of N⁵-dimethyl-Gln⁶]-SP_5–11 showed 37±12% contractile activity relative to SP, and intrinsic efficacy 98±4%. This finding indicates that the carboxamide groups of the dual Gln⁵-Gln⁶ moiety are not equally related with the contractile response of the C-terminal heptapeptide of SP.The authors wish to express their deep appreciation to Professor H. Niedrich and Dr J. Bergmann of the Institute of Drug Research, Academy of Sciences of DDR, Berlin, for their valuable help in providing the biological data.