1-Methylhydantoin is a small molecular weight polar substance the product of degradation of creatinine by bacteria. In mammals the metabolism of 1-methylhydantoin occurs via 5-hydroxy-1-methylhydantoin. In a reported human case 1-Methylhydantoin was found as an unexpected metabolite of the intelligence-affecting substance dupracetam.

C-Peptide 2, rat, 31-amino-acid peptide, is a component of proinsulin. C-Peptide 2, rat can inhibit glucose-induced insulin secretion.

This is amino acids 86 to 100 fragment of class II-associated invariant chain peptide called CLIP. The major histocompatibility complex class II molecule displays peptide fragments of foreign proteins to trigger a defensive reaction from the immune system. Before insertion of the foreign peptides into the binding groove, a place-holding peptide CLIP is removed. This is accomplished by the molecule DM, which is shown to increase the dissociation rate of a CLIP peptide from class II.