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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.

Storage Class Code

12 - Non Combustible Liquids



Flash Point(F)

does not flash

Flash Point(C)

does not flash

Certificate of Analysis

Certificate of Origin

Related Content

Klenow Enzyme Protocol

Protocols of standard assays for partial and complete filling in can be found in LabFaqs.

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