DiaPharma Group, Inc.

For research use only.

S-2302 is a chromogenic substrate for plasma kallikrein. The substrate has been used for the determination of:

1. Prekallikrein in plasma
2. Kallikrein inhibitors in plasma
3. FXII in plasma
4. Kallikrein-like activity in plasma
5. Prekallikrein activator in albumin and immunoglobulin preparations

Reagent -- Composition, Packaging, Storage and Stability

Each vial contains chromogenic substrate S-2302 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: 4 mmol/l in H2O is stable for more than 6 months at 2-8°C.

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

Chemistry

Chemical name: H-D-Prolyl-L-phenylalanyl-Larginine-p-nitroaniline dihydrochloride.

S-2302 structure

Formula: H-D-Pro-Phe-Arg-pNA·2HCl

Mol. wt: 611.6

e316 nm: 1.27 · 104 mol-1 · L · cm-1

Solubility: > 10 mmol/l in H2O

Suitable stock solution: 4 mmol/l in H2O.

Principle

	Enzyme
H-D-Pro-Phe-Arg-pNA		H-D-Pro-Phe-Arg OH+pNA(yellow)

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.

Kinetic Data

Human plasma kallikrein: Km= 2 · 10-4 mol/l, V = 6.8 · 10-6 mol/min · PEU. Determined at 37°C in 2.5 ml of 0.05 mol/l Tris buffer pH 7.8 I 0.05. PEU (Plasma Equivalent Units). PEU refers to the activity generated from 1 ml of normal human plasma using Cephotest® as activator. The same Km was obtained for a highly purified human plasma kallikrein.