Is the presence of biotinylated proteins in the host organism in case of proteins expressed in the cytoplasm a problem?
No. Generally, the cell internal content of biotinylated proteins and free biotin is rather low and not a threat for significant inactivation of the Strep-Tactin resin. Therefore, no avidin has necessarily to be added to the extract when purification is intended. Example: An E. coli extract derived from a 1 l culture with OD550 = 1 has a total biotin content of around 1 nmol only (biotin capacity ≅ 350 nmol/ml sedimented resin). • Is the presence of free biotin in the medium (in case of proteins secreted to the medium) a problem (eukaryotic expression)? Free Biotin inactivates Strep-Tactin resins (biotin capacity ≅ 350 nmol/ml sedimented resin) and has to be removed or masked prior to affinity chromatography. This is mostly relevant when cell culture supernatant, containing secreted recombinant protein, is directly subjected to Strep-Tactin affinity chromatography because some media for insect cells or mammalian cells contain significant amounts of biotin (see table below). The simples
Related Questions
- Is the presence of free biotin in the medium (in case of proteins secreted to the medium) a problem (eukaryotic expression)?
- Is the presence of biotinylated proteins in the host organism in case of proteins expressed in the cytoplasm a problem?
- For proteins expressed in the cytoplasm, is the presence of biotinylated proteins in the host organism a problem?
