New England Biolabs supplies a 10X reaction buffer for use with Klenow Fragment (3´→5´ exo^–).

At a 1X concentration this reaction buffer assures optimal activity of the enzyme.

1X Buffer Components

10 mM Tris-HCl

10 mM MgCl₂

50 mM NaCl

1 mM DTT

0.2 mM dATP

pH 7.9@25°C

-20°C