E.coli SS Binding Protein (0.545mL)

A single-stranded DNA binding protein from QIAGEN, produced recombinantly in an E. coli strain carrying the E. coli ssb gene. The enzyme preferentially binds single-stranded DNA, forming a tetramer of four identical 18.9 kDa subunits that protects 8–16 nucleotides, while not binding well to double-stranded DNA. In nature, the protein participates in DNA replication, recombination, and repair; in vitro, it has been found to stimulate specific DNA polymerase-mediated reactions by relaxing DNA secondary structure and enhancing enzyme processivity.

The protein is supplied at a concentration of 2.75 mg/mL in 50 mM Tris-HCl, 200 mM NaCl, 1 mM DTT, 0.1 mM EDTA, and 50% glycerol (pH 7.5 at 25°C) and should be stored between -25°C and -15°C. Quality control testing confirms >99% purity by SDS-PAGE with silver stain detection. Nuclease activities meet specification: single-stranded exonuclease <1.0% released at 25 µg tested, double-stranded exonuclease <1.0% released at 25 µg tested, and double-stranded endonuclease showing no conversion at 25 µg tested. DNA binding ability is confirmed in a PCR inhibition assay, with an acceptance criterion of 0.70 µg required to inhibit PCR amplification of 5 ng target DNA after 25 cycles.

Applications include stabilization of single-stranded DNA regions, enhancement of DNA polymerase fidelity and processivity in PCR, minimization of deletion mutagenesis artifacts during Taq DNA polymerase-mediated PCR, improvement of DNA amplification yield, and enabling sequencing of problematic templates such as those with strong secondary structures. A recommended starting concentration for SSB-mediated PCR reactions is 20–320 ng/μL per 50 µL reaction. The product is for in vitro use only and is not suitable for administration to humans or animals.