Dissociation of biotin from streptavidin is very difficult due to their high binding affinity. The re-use of streptavidin-modified surfaces is therefore almost impossible, making devices containing them (e.g. surface plasmon resonance (SPR) sensor chips) expensive. This paper describes a new protocol for reversible and site-directed immobilization of proteins with streptavidin affinity tags on the streptavidin-coated SPR biosensor chip (SA chip). Two streptavidin affinity tags, nano-tag and streptavidin-binding peptide (SBP tag), were applied. They both can specifically interact with streptavidin but have weaker binding force compared to the biotin–streptavidin system, thus allowing association and dissociation under controlled conditions. The SA chip surface could be regenerated repeatedly without loss of activity by injection of 50 mM NaOH solution. The fusion construct of a SBP tag and a single-chain antibody to mature bovine prion protein (scFv-Z186-SBP) interacts with the SA chip, resulting in a single-chain-antibody-modified surface. The chip showed kinetic response to the prion antigen with equilibrium dissociation constant KD≈4.01×10−7. All results indicated that the capture activity of the SA chip has no irreversible loss after repeated immobilization and regeneration cycles. The method should be of great benefit to various biosensors, biochips and immunoassay applications based on the streptavidin capture surface.
Surface plasmon resonance Streptavidin affinity tag Nano-tag Site-directed immobilization Regeneration
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The study is supported by the Chinese Academy of Sciences and the Ministry of Science and Technology.
1.Joint research group on analytical biotechnology of State Key Laboratory of MacromoleculesInstitute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China and State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of SciencesWuhanChina
2.Graduate SchoolChinese Academy of SciencesBeijingPeople’s Republic of China