L-Thr-L-Pro-L-Arg-L-Lys-OH

N2-[N2-(1-L-Threonyl-L-prolyl)-L-arginyl]-L-lysine

(2S)-6-amino-2-[[(2S)-2-[[(2S)-1-[(2S,3R)-2-amino-3-hydroxy-butanoyl]pyrrolidine-2-carbonyl]amino]-5-(diaminomethylideneamino)pentanoyl]amino]hexanoic acid