75903-15-0 L-Leucine, N-(N-(N2-(N2-(N2-(N-(N-(1-(N-(N2-(N-L-leucyl-L-valyl)-L-lysyl)-L-valyl)-L-prolyl)-L-leucyl)-L-valyl)-L-arginyl)-L-lysyl)-L-lysyl)-L-seryl)- Pepsinogen (1-12)