The plasmin substrate provide by our company is chemically and functionally identical to Chromogenix S-2251. Each 25 mg of substrate is lyophilized with 60 mg mannitol as a bulking agent. Formula: H-D-Val-Leu-Lys-pNA . 2HCl Mr: 551.6 Da Gene ID: 5340 Swiss-Prot/UniProt ID: P00747