64816-14-4 D-Valyl-leucyl-arginine-p-nitroanilide H-D-Val-leu-arg-p-nitroanilide L-Argininamide, D-valyl-L-leucyl-N-(4-nitrophenyl)- S 2266 S-2266 S2266 Val-Leu-Arg-p-nitroanilide