GLUCOSE DEHYDROGENASE (NAD(P)-dependent) from Microorganism

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Appearance :White amorphous powder, lyophilized.
Activity :Grade Ⅲ 250 U/mg-solid or more
Stability :Stable at −20 ℃ for at least one year
Molecular weight :approx. 101,000 (Gel filtration)
Isoelectric point :4.5
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PREPARATION and SPECIFICATION

AppearanceWhite amorphous powder, lyophilized.
ActivityGradeⅢ 250 U/mg-solid or more
ContaminantsNADH oxidase≤1.0×10-3 %
α-Glucosidase≤1.0×10-3 %
Glucose-6-phosphate dehydrogenase≤1.0×10-3 %

PROPERTIES

StabilityStable at −20 ℃ for at least one year(Fig.1)
Molecular weightapprox. 101,000 (Gel filtration)
Isoelectric point4.5
Michaelis constantsNADlinked1.38×10-2 M (D-Glucose) 3.09×10-4 M (NAD)
NADPlinked1.25×10-2 M (D-Glucose) 4.07×10-5 M (NADP+)
InhibitorsAg, Hg2+, Monoiodoacetate
Optimum pH9.0(Fig.4)
Optimum temperature55 ℃(Fig.5)
pH StabilitypH 6.0−7.5 (20 ℃, 16 hr)(Fig.6)
Thermal stability45 ℃ (15 min-treatment with 50 mM K-phosphate buffer, pH 7.0)(Fig.7)
Substrate specificitySpecific for β-D-Glucose or 2-Deoxy-glucose (Table.1) (Either NAD or NADP serves as coenzyme.)

APPLICATIONS

This enzyme is useful for enzymatic determination of D-glucose.

ASSAY

Principle

Principle

The formation of NADH is measured at 340 nm by spectrophotometry.

Unit definition

One unit causes the formation of one micromole of NADH per minute under the conditions detailed below.

Method

Reagents

A. Tris-HCl buffer, pH 8.00.1 M
B. D-Glucose solution1.5 M
C. β-NAD+ solution80 mg/mL
D. Enzyme diluent50 mM K-phosphate buffer, pH 7.0 contg. 0.1 % BSA

Procedure

1.Prepare the following reaction mixture in a cuvette (d = 1.0cm) and equilibrate at 37 ℃ for approximately 5 minutes.

2.6 mLTris-HCl buffer, pH 8.0(A)
0.3 mLSubstrate solution(B)
0.1 mLβ-NAD+ solution(C)
Concentration in assay mixture
Tris-HCl buffer85.25 mM
D-Glucose147.54 mM
NAD3.66 mM

2.Add 0.05 mL of the enzyme solution* and mix by gentle inversion.

3.Record the increase in optical density at 340 nm against water for 2 to 5 minutes with a spectrophotometer thermostated at 37 ℃, and calculate the ΔOD per minute from the initial linear portion of the curve (ΔOD test).
At the same time, measure the blank rate (ΔOD blank) using the same method as the test except that the enzyme diluent (D) is added instead of the enzyme solution.

*Dissolve the enzyme preparation in ice-cold enzyme diluent (D), dilute to 0.8−1.2 U/mL with the same buffer and store on ice.

Calculation

Activity can be calculated by using the following formula :

  • Volume activity (U/mL) =

  • ΔOD/min (ΔOD test−ΔOD blank)×Vt×df


    6.22×1.0×Vs

  • = ΔOD/min×9.807×df

Weight activity (U/mg) = (U/mL)×1/C

Vt: Total volume (3.05 mL)
Vs: Sample volume (0.05 mL)
6.22: Millimolar extinction coefficient of NADH under the assay conditions (cm2/micromole)
1.0: Light path length (cm)
df: Dilution factor
C: Enzyme concentration in dissolution (c mg/mL)

Table 1. Substrate Specificity of Glucose dehydrogenase

  • Substrate (150mM)Relative activity(%)
    D-Glucose100.0
    L-Glucose0.0
    D-Xylose16.2
    2-Deoxy-glucose127.0
    L-Sorbose0.0
    D-Mannose5.1
    D-Fructose0.0
  • Substrate (150mM)Relative activity(%)
    Galactose1.7
    D-Lactose1.5
    D-Sorbitole0.0
    D-Mannitol0.0
    Sucrose0.0
    Inositol0.0
    Maltose1.4

Table 2. Effect of Various Chemicals on Glucose dehydrogenase

[The enzyme dissolved in 50 mM K-phosphate buffer, pH 7.0 (2.8 U/mL) was incubated with each chemical for 1 hr at 30 ℃.]

  • ChemicalConcn.(mM)Residual
    activity(%)
    None100
    Metal salt2.0
    AgNO37.1
    Ba(OAc)298.2
    CaCl298.9
    Cd(OAc)296.6
    CoCl296.4
    CuSO499.5
    FeCl398.1
    FeSO496.6
    HgCl25.9
    MgCl2101.5
    MnCl2100.9
    NiCl293.4
    Pb(OAc)299.8
    ZnSO4102.1
  • ChemicalConcn.(mM)Residual
    activity(%)
    KF2.098.7
    NaF10.0100.6
    NaN320.0101.6
    NEM2.097.6
    MIA2.00.4
    IAA2.092.2
    EDTA5.0107.2
    (NH4)2SO420.096.0
    Borate20.0101.4
    o-Phenanthroline2.097.7
    α,α′-Dipyridyl1.0100.3
    Urea2.0122.5
    Guanidine2.099.2
    Hydroxylamine2.0107.2

Ac, CH3CO; NEM, N-Ethylmaleimide; MIA, Monoiodoacetate; IAA, lodoacetamide; EDTA, Ethylenediaminetetraacetate.

  • Fig.1. Stability (Powder form)

    Fig.1. Stability (Powder form)

    (kept under dry conditions)

  • Fig.2. Stability (Powder form)

    Fig.2. Stability (Powder form)

    (kept under dry conditions)

  • Fig.3. Stability (Liquid form)

    Fig.3. Stability (Liquid form)

    25 ℃,in 83 mM Tris-HCI buffer solution pH 8.0(contg.3.7 mM β-NAD,40 U/mL mutarotase) enzyme concn.:300 U/mL

  • Fig.4. pH-Activity

    Fig.4. pH-Activity

    37 ℃,5 min-reaction in 80 mM buffer solution
    ●:pH 6.0-8.0 K-phosphate
    ○:pH 8.0-9.0,Tris-HCI
    ■:pH 8.5-10.5 Carbonate

  • Fig.5. Temperature activity

    Fig.5. Temperature activity

    (in 80 mM Tris-HCI buffer, pH 8.0)

  • Fig.6. pH-Stability

    Fig.6. pH-Stability

    20 ℃,16 hr with 0.1 M buffer solution
    ●:pH 4.0-6.0 acetate
    ○:pH 6.0-8.0 K-phosphate
    ■:pH 7.5-9.0 Tris-HCI
    □:pH 8.5-10.5 carbonate
    enzyme concn.:10 U/mL

  • Fig.7. Thermal stability

    Fig.7. Thermal stability

    15 min-treatment with 50 mM K-phosphate buffer pH 7.0 enzyme concn.: 12 U/mL

2. MSDS

3. Tech Data Sheets/Manuals

Size

1 MG, 10 MG, 5 MG

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