Klenow Enzyme

Labeling grade, from Escherichia coli lysogenic NM 964

Enzyme Commission number:

Quality Level



specific activity

>5000 units/mg protein


pkg of 100 U (11008404001)
pkg of 500 U (11008412001)



shipped in

dry ice

storage temp.


General description

Klenow enzyme is a DNA-dependent 5′→3′ polymerase with 3′→5′ exonuclease activity. It lacks the 5′→3′ exonuclease activity of the native enzyme. The addition of mononucleotides from dNTPs to the 3′-OH terminus of DNA is catalyzed. This property is used to synthesize DNA complementary to single-stranded DNA templates.


Heat inactivation: Add 2 μl 0.2 mM EDTA (pH 8.0) and/or heat to 65 °C for 10 minutes


Use Klenow Enzyme for:
  • Random-primed DNA labeling using random oligonucleotides as primers for the incorporation of nonradioactively labeled and 32P-labeled nucleotides.
  • Fill-in reaction for blunt-end formation of 3′-recessed (staggered) ends.


Absence of endo- and exonuclease activity tested according to the current Quality Control procedures

Unit Definition

One unit is the enzyme activity which incorporates 10 nmol of total nucleotides into an acid-precipitable fraction in 30 minutes under assay conditions at +37 °C with poly [d(A-T)] as primer (Richardson, C.C. & Kornberg, A. (1994) J. Biol. Chem. 244, 2996).

Volume Activity: 2,000 U/ml

Physical form

Enzyme in Storage buffer: 50mM potassium phosphate, 1mM dithioerythritol, 50% glycerol (v/v), pH 7.0 (+4°C).

Other Notes

For life science research only. Not for use in diagnostic procedures.


NONH for all modes of transport

Certificate of Analysis

Certificate of Origin

Klenow Enzyme Protocol
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