3-methylthiopropionate is one of the metabolites of methionine (especially of D-methionine). Cultures of Streptomyces lincolnensis accumulated 3-methylthioacrylic acid in amounts directly related to the concentration of methionine in the medium. The first intermediate in the pathway may be the keto acid which is then oxidatively decarboxylated to 3-methylthiopropionic acid.

H-Phe-Pro-Arg-OH

Schistoflrfamide, a FMRFamide-related peptide, is an inhibitory neuropeptide. Schistoflrfamide decreases the amplitude and frequency of myogenic contractions and reduce basal tension visceral muscle.