Tuftsin diacetate, a tetrapeptide, is a macrophage/microglial activator. Tuftsin is a tetrapeptide, Thr-Lys-Pro-Arg, which resides in the Fc-domain of the heavy chain of immunoglobulin G. Tuftsin possesses a broad spectrum of activities related primarily to the immune system function and exerts on phagocytic cells, notably on macrophages.

Enterostatin, human, mouse, rat is a pentapeptide that reduces fat intake.

Beta-leucine?is a beta-amino acid that is?pentanoic acid?substituted at positions 3 and 4 by?amino?and?methyl?groups respectively.