M13KO7 concentrated


Price (USD): $215.00

M13KO7 Helper Phage (concentrated)

Technical Description

M13KO7 is a helper phage designed for the production of single-stranded plasmid DNA (1). M13KO7 is an M13 phage that has the insertion of the origin of replication from p15A and the kanamycin-resistance gene from Tn 903 at the AvaI site at position 5825 of M13. M13KO7 does not contain the Met40Ile mutation in protein g2p as initially reported (1). Virions prepared with M13KO7 have a phagemid/helper ratio of around 9:1.


  • Preparation of ssDNA from phagemid vector.

  • Phage display.

For research use only; not intended for any animal or human therapeutic or diagnostic use.


M13KO7 virions were isolated from the supernatant of infected E. coli TG1 cells and purified by PEG precipitation.


Composition: 50% glycerol TBS buffered.
Concentration: 2 x1012 pfu/ml; 1.25 x1013 virions/ml; infectivity ~16%
Storage temperature: -20°C.
Product size: 1 ml.

Quality Control & Certification of Analysis

Virion concentration:

Phage DNA concentrations are determined by UV spectrophotometry and virion concentrations calculated based on the length of M13KO7 genome.

Phage titer:

M13KO7 preparations are serially diluted and mixed with melted LB top agar and TG1 cells. The mixtures are poured over LB bottom agar plates and incubated overnight at 37°C; the morning after plaques are counted. Controls include plates without virions and have no visible plaques.


Infectivities are counted as the ratio between phage titer and virion concentration. Infectivities superior or equal to 15% are expected.

Gene II ORF sequence:

ORF DNA is amplified by PCR and sequenced.

Absence of defective interfering (DI) particles:

Integrity of phage particle ssDNA is verified by electrophoresis.


Products meet all specifications.


  1. Vieira, J. and Messing, J. (1987) R. Wu and L. Grossman (Eds.), Methods Enzymol., 153, pp. 3-11. San Diego: Academic Press.

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