Product Details
Form: Freeze-dried
Solubility: Readily soluble in distilled water or dilute buffer
Stability: -20° C; -4° F
Activity: 10 U/mg protein
Protein: 60%
Unit Definition
One unit will cause an increase in A232.5 of 0.001 per minute at pH 9.0 at 25°C when linoleic acid is the substrate in 3.0 ml volume (1 cm light path). One A232.5 unit is equivelent to the oxidation of 0.12 µmol of linoleic acid.
Applications
Lipoxidase (EC 1.13.11.12) catalyzes the oxidation of polyunsaturated fatty acids containing cis,cis-1,4-pentadiene systems to form hydroperoxides. The degradation of the hydroperoxide by the lipoxidase seems to prevent the breakdown of amino acids and proteins which are associated with an odorous carbyl compound which produces the beany flavor found in many legumes.
Lipoxidase is widely distributed, especially concentrated in the legumes. Soybeans have been found to have the highest concentrations while isoenzymes have been reported in cowpeas.
Reagents
- 0.1 M ammonium hydroxide ammonium chloride buffer, pH 9.0
- 1 mM Linoleic acid
- 20 µl Lipoxydase diluted to 0.6 U/ml
Procedure
- Set spectrophotometer (equipped with a strip chart recorder and temperature control) at 232.5 nm and 25°C
- Into the quartz cuvettes pipette 2.9 ml ammonium hydroxide ammonium chloride buffer
- Add 0.1ml of the enzyme solution to the test cuvette, mix, and record the rate of absorbance at 232.5 nm for 5 minutes.
- Calculate the ÆE232.5nm/min from the initial linear portion of the curve.