A novel peptide, pyroglutamylglutamylproline amide, in the rabbit prostate complex, structurally related to thyrotrophin-releasing hormone.

A novel peptide which cross-reacts with an antibody to thyrotrophin-releasing hormone has been isolated and characterized from the rabbit prostate complex. The peptide exhibited an amino acid composition of Glx1.7, Pro1.0, and automatic gas phase sequence analysis after mild acid hydrolysis established the sequence Glu-Glu-Pro. Fast atom bombardment mass spectrometry gave a pseudomolecular ion (M + H)+ of 355.2 confirming that the prostate peptide has the structure of pGlu-Glu-Pro-NH2. This peptide differs from authentic thyrotrophin-releasing hormone by the substitution of glutamic acid for histidine at position 2.