Na2HPO4 – NaH2PO4 Buffer Solutions, pH 5.8–8.0 at 25 °C1

Na2HPO4 • 2H2O, M. wt. 178.05; 0.2M-solution contains 35.61 g/l. Na2HPO4 • 12H2O, M. wt. 358.22; 0.2M -solution contains 71.64 g/l. NaH2PO4 • H2O, M. wt. 138.01; 0.2M-solution contains 27.6 g/l. NaH2PO4 • 2H2O, M. wt. 156.03; 0.2M-solution contains 31.21 g/l.

x ml 0.2M-Na2HPO4, y ml 0.2M-NaH2PO4; diluted to 100 ml with H2O.

Class I contains genes involved in most metabolic processes. Class II genes correspond to genes highly and continuously expressed during exponential growth. Class III genes are implicated in horizontal transfer of DNA

1. Adjust  purified Taq  (4 ⁰C) to A₂₈₀= 1 in absorbance and 9.0 in pH with buffer containing 50 mM Tris, pH 9.0, 0.1 mM EDTA, and 0.01% Tween.

2. Add 50 ml of 27 mM citraconic anhydride (CA) in DMF  to 1 liter of Taq (100:1).

3. Stir the mixture for 60 minutes at 4 ⁰C.

4. Other ratio: 800:1 400:1, 200:1, 100:1, 50:1 and 20:1.
 

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