CBL (Cystathionine-β-lyase)
This enzyme is useful for enzymatic determination of L-homocysteine when coupled with CBS and LDH in clinical analysis.
Specification
|
Appearance |
Yellow amorphous powder, lyophilized |
|
Purity(SDS-PAGE) |
≥90.0% |
|
Enzyme powder specific activity |
≥30.0 U/mg |
|
Glucose-6-phosphate dehydrogenase |
≤0.01% |
|
Lactate dehydrogenase |
≤0.01% |
Properties
|
EC number |
4.4.1.8 (Recombinant from microorganism) |
|
Molecular weight |
54 kDa (SDS-PAGE) |
|
Isoelectric point |
6.0 |
|
Michaelis constants |
1.6 ×10-3 M (L-Cystathionine) |
|
Inhibitors |
Not inhibited by NaN3 |
|
Optimum pH |
8.0 Fig. 1 |
|
Optimum temperature |
50 ℃ Fig. 2 |
|
pH stability |
pH 6.0-10.0 (25 ℃, 16 h) Fig. 3 |
|
Thermal stability |
Below 45℃ (pH 8.0, 30 min) Fig. 4 |
|
Storagestability |
At least one year at -25 ～-15 ℃ Fig. 5 |
|
Stabilizers |
Triton X-100, glycerol |
Storage condition
Store at -25~-15°C, sealed, dry and protected from light. Valid for 1 year.
Figures
Assay principle
Unit definition
One unit (U) is defined as the amount of enzyme which consumes 1 μmol of NADH per min under the conditions described below.
Reagents preparation
Reagent I: 100 mM pH 8.0 Tris-HCl buffer, contains 3.5 mM DL-Cystathionine , 0.15 mM NADH, 0.05 mM PLP, 10 U/mL LDH.
Enzyme diluent: 50 mM pH 8.0 Tris-HCl buffer.
Sample: The enzyme was diluted to 0.8-2.4 U/mL with the enzyme diluent.
Procedure
1. Add 1 mL Reagent I to the 1 mL cuvette and preheat it at 37℃ for 5 min.
2. Add 0.02 mL enzyme solution to the cuvette and mix.
3. Record the ΔAs at 340 nm in 1 minute in a spectrophotometer thermostated at 37℃ .
At the same time, measure the blank rate ΔAb by using the same method as the test except that the enzyme diluent is added instead of the enzyme solution.
∆A = ∆As - ∆Ab
Calculation
1.02: Total volume (mL)
0.02: enzyme volume (mL)
1.0: Light path length (cm)
df: dilution factor 6.22: Millimolar extinction coefficient of NADH under 340nm (cm2/μmol)
