137132-73-1 L-Lysine, N2-(1-(N2-(N2-(N-L-valyl-L-alanyl)-L-lysyl)-L-lysyl)-L-prolyl)- N2-(1-(N2-(N2-(N-L-Valyl-L-alanyl)-L-lysyl)-L-lysyl)-L-prolyl)-L-lysine P23 Sperm acrosomal peptide Sperm acrosomal peptide P23 Val-ala-lys-lys-pro-lys