DiaPharma Group, Inc.

For research use only

S-2251 is a chromogenic substrate for plasmin and streptokinase-activated plasminogen. The substrate has been used for the determination of:

1. Antiplasmin in plasma
2. Plasminogen in plasma

Reagent -- Composition, Packaging, Storage and Stability

Each vial contains chromogenic substrate S-2251, 25 mg and mannitol 60 mg as a bulking agent. Stability: Substance: Stable until expiry date if stored at 2-8°C. Avoid exposure to light. The substance is hygroscopic and should be stored dry. Solution: 3 mmol/L in H2O is stable for at least 6 months at 2-8°C. Contamination by microorganisms may cause hydrolysis.

** Also available in bulk sizes (500+ mg) as a special order.

Chemistry

Chemical name: H-D-Valyl-L-leucyl-L-lysinep-Nitroaniline dihydrochloride

S-2251 structure

Formula: H-D-Val-Leu-Lys-pNA · 2HCl

Mol. wt: 551.6

e316 nm: 1.27 · 104 mol-1 · L · cm-1

Solubility: > 40 mmol/L in H2O

Suitable stock solution: 3-4 mmol/L in H2O.

Principle

	Enzyme
H-D-Val-Leu-Lys-pNA		H-D-Val-Leu-Lys-OH+pNA

The method for the determination of activity is based on the difference in absorbance (optical density) between the pNA formed and the original substrate.

The rate of pNA formation, i.e. the increase in absorbance per second at 405 nm, is proportional to the enzymatic activity and is conveniently determined with a photometer.

Crystalization of S-2251

Kinetic Data

Plasmin (human): Km= 3 · 10-4 mol/L, V= 0.5 · 10-6 mol/min · CU

Plasminogen - SK: Km= 2 · 10-4 mol/L, V= 1 · 10-6 mol/min · mL plasma.

Determined at 37°C in 2.5 mL 0.05 mol/L Tris buffer pH 7.4, I 0.5.

Standardization

An activity of DA/min=0.05 (37°C) is obtained by using a substrate concentration of 2 · km and:

1. 0.010 CU/mL of human plasmin from Chromogenix AB.
2. 0.0011 U/mL of the plasmin standard from NIBSC, Potters Bar, London.
3. 0.0078 CU/mL of SK-activated human plasminogen from Chromogenix AB. The substrate is insensitive to kallikrein (glandular and plasma) and urokinase.