Human liquor means waste content from bowels isolated to investigate specific enzymes and peptidases involved in enteric contraction and digestion of compounds. P-endopeptidase isolated from human liquor inactivates tachykinins. Hydrolysis of Substance P by P-endopeptidase yields the active fragment of substance P. A neuroactive peptide, Substance P is found throughout the central and peripheral nervous system. It has mostly been studied for its contractive effect on enteric musculature. References Nyberg et al. 1984 Physiology