H-Leu-Trp-Met-Arg-OH is a tetrapeptide. H-Leu-Trp-Met-Arg-OH can be used as a substrate for aminopeptidase-mediated hydrolysis studies[1].
References
[1] Vilaseca M, et al. Reduction of methionine sulfoxide with NH4ITFA: Compatibility with peptides containing cysteine and aromatic amino acids[J]. Tetrahedron, 1998, 54(50): 15273-15286.