N-ACETYLNEURAMINIC ACID ALDOLASE from Microorganism

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Appearance : Yellowish amorphous powder, lyophilized
Activity : Grade Ⅲ 15 U/mg-solid or more (30 U/mg-protein or more)
(containing approx. 30 % of stabilizers)
Contaminants : Catalase ≤ 1.0 %
NADH oxidase ≤ 1.0×10-3 %
Stabilizers : Mannitol, EDTA
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PREPARATION and SPECIFICATION

Appearance Yellowish amorphous powder, lyophilized
Activity GradeⅢ 15 U/mg-solid or more (30 U/mg-protein or more)
(containing approx. 30 % of stabilizers)
Contaminants Catalase ≤ 1.0 %
NADH oxidase ≤ 1.0×10-3 %
Stabilizers Mannitol, EDTA

PROPERTIES

Stability Stable at 20 ℃ for at least one year(Fig.1)
Molecular weight approx. 98,000
Isoelectric point 4.6±0.1
Michaelis constant 2.5×10-3 M (N-Acetylneuraminic acid)
Structure 3 subunits (approx. 35,000) per enzyme molecule
Inhibitors p-Chloromercuribenzoate, SDS, Hg2+, Ag
Optimum pH 7.58.0(Fig.3)
Optimum temperature 70 ℃(Fig.4)
pH Stability pH 6.09.0 (10 ℃, 25 hr)(Fig.5)
Thermal stability below 65 ℃ (pH 7.5, 30 min)(Fig.6)
Effect of various chemicals (Table 1)

APPLICATIONS

This enzyme is useful for enzymatic determination of N-acetylneuraminic acid and sialic acid in combination with related enzymes, in clinical analysis. 57)
In industrial use, this enzyme is useful for enzymatic synthesis of sialic acid. 89)

ASSAY

Principle

Principle

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

Unit definition

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

Method

Reagents

A. NANA solution 50 mM: Dissolve 309 mg of N-acetylneuraminic acid (MW = 309) in approx. 15 mL of 50 mM potassium phosphate buffer, pH 7.5, and, after adjusting the pH to 7.5 with 1 N KOH, make up to 20 mL with the same buffer (stable for at least 1 week if stored at 0 5 ℃).
B. LDH solution Approx. 50 U/mL: Dilute pig heart lactate dehydrogenase (Toyobo, grade II, ammonium sulfate suspension) to approx. 50 U/mL with ice-cold 50 mM potassium phosphate buffer, pH 7.5 (should be freshly prepared).
C. NADH solution 1.0 mM: Dissolve 7.6 mg of NADH・Na2・3H2O (MW = 763) in 10 mL of 50 mM potassium phosphate buffer, pH 7.5 (should be freshly prepared).
D. Buffer solution 50 mM potassium phosphate buffer pH 7.5
E. Enzyme diluent 50 mM potassium phosphate buffer pH 7.5, containing 0.2 % BSA

Procedure

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

1.0 mL Substrate solution (A)
0.5 mL LDH solution (B)
0.5 mL NADH solution (C)
0.4 mL Buffer solution (D)
Concentration in assay mixture
Potassium phosphate buffer 50 mM
NANA 20 mM
NADH 0.2mM
LDH Approx. 10 U/mL

2.Add 0.1 mL of the enzyme solution* and mix by gentle inversion.

3.Record the decrease in optical density at 340 nm against water for 3 to 4 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 in the test except that the enzyme diluent (E) is added instead of the enzyme solution.

*Dissolve the enzyme preparation in ice-cold enzyme diluent (E) and dilute to 0.10.3 U/mL with the same buffer, immediately before the assay.

Calculation

Activity can be calculated by using the following formula :

  • Volume activity (U/mL) =

  • ΔOD/min (ΔOD testΔOD blank)×Vt×df


    6.22×1.0×Vs

= ΔOD/min×4.02×df

Weight activity (U/mg) = (U/mL)×1/C

Vt : Total volume (2.5 mL)
Vs : Sample vol ume (0.1 mL)
6.22 : Millimolar extinction coefficient of NADH (cm2/micromole)
1.0 : Light path length (cm)
df : Dilution factor
C : Enzyme concentration in dissolution (c mg/mL)

REFERENCES

1)D.G.Comb and S.Roseman; J.Biol.Chem., 235, 2529 (1960).

2)D.G.Comb and S.Roseman; Meth.Enzymol., 5, 391 (1960).

3)S.B.Arden, W.Chang and L.Barksdale; J.Bacteriol., 112, 1260 (1972).

4)Y.Uchida, Y.Tsukada and T.Sugimori; Agric.Biol.Chem., 49, 181 (1985).

5)P.Burunetti, A.Swanson and S.Roseman; Meth.Enzymol., 6, 465 (1963).

6)K.Taniuchi, Y.Miyamoto, Y.Uchida, K.Chifu, M.Mukai, N.Yamaguchi, Y.Tsukada, T.Sugimori, K.Doi and S.Baba; J.Med.Technol. (Japanese), 7, 403 (1979).

7)K.Sugahara, K.Sugimoto, O.Nomura and T.Usui; Clin.Chim.Acta, 108, 493 (1980).

8)Mahn-Joo Kim,William J.Hennen,H.Marcel Sweers and Chi-Huey Wong; J.Am.Chem.Soc.,110, 6481 (1988).

9)Ethan S.Simon,Mark D.Bednarski,and George M.Whitesides; J.Am.Chem.Soc.,110, 7159 (1988).

Table 1. Effect of Various Chemicals on N-Acetylneuraminic acid aldolase

[The enzyme dissolved in 0.1 M Tris-HCI buffer, pH 7.5 (5 U/mL) was incubated at 30 ℃ for 1hr.]

  • Chemical Concn.(mM) Residual activity(%)
    None 100
    Metal salt 2.0
    MgCl2 107
    CaCl2 87
    Ba(OAc)2 95
    FeCl3 89
    CoCl2 93
    MnCl2 98
    ZnSO4 92
    NiCl2 99
    CuSO4 64
    Pb(OAc)2 87
    AgNO3 0
    HgCl2 0
  • Chemical Concn.(mM) Residual activity(%)
    PCMB 2.0 0
    NEM 2.0 103
    NaF 2.0 100
    NaN3 20 100
    EDTA 5.0 95
    o-Phenanthroline 2.0 100
    α,α′-Dipyridyl 2.0 101
    Borate 50 86
    Triton X-100 0.10 % 109
    Na-cholate 0.10 % 95
    SDS 0.10 % 0
    Tween 40 0.10 % 96
    Span 85 0.10 % 93
Ac, CH3CO; PCMB, p-Chloromercuribenzoate; NEM, N-Ethylmaleimide; EDTA, Ethylenediaminetetraacetate;SDS, Sodium dodecyl sulfate.
  • 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. pH-Activity

    Fig.3. pH-Activity

    37 ℃, 5 min-reaction in 50 mM buffer solution : pH 5.0-6.0, acetate; pH 6.0- 9.0, K-phosphate; The enzyme activity was assayed by the 2,4-dinitroplenylhydradine method.

  • Fig.4. Temperature activity

    Fig.4. Temperature activity

    5 min-reaction in 50 mM K-phosphate buffer pH 7.5, The enzyme activity was assayed by the 2,4-dinitroplenylhydradine method.

  • Fig.5. pH-Stability

    Fig.5. pH-Stability

    10 ℃, 25 hr-treatment with 50 mM buffer solution : pH 4.0-6.0, acetate; pH 6.0-9.0, K-phosphate ; pH 9.0-10.0, borate.

  • Fig.6. Thermal stability

    Fig.6. Thermal stability

    30 min-treatment with 50 mM K-phosphate buffer, pH 7.5, enzyme concentration.: 20 U/mL

2. MSDS

3. Tech Data Sheets/Manuals

Size

1 MG, 10 MG, 5 MG

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