Streptrap hp 5 ml

Expression and purification of His-tagged proteins were performed as described^{23 (link),24 (link),26 (link)}. E. Coli BL21-Gold (DE3) Competent Cells (Agilent Technologies) were transformed with the plasmid coding for the different proteins. Cells were grown at 37 °C in 2YT medium containing 200 µg.L⁻¹ ampicillin until the OD_600nm reached 0.6. Protein expression was induced by addition of 1 mM IPTG and the cells were further incubated for 5 h at 37 °C. The cells were harvested, suspended in 50 mM sodium phosphate pH7.5, 150 mM NaCl (PBS), submitted to three freezing/thawing cycles, treated with DNase I for 30 min and sonicated. The His-tagged proteins were purified using nickel-affinity chromatography (Histrap™ FF crude 5 mL, GE Healthcare). The His-tag A3-A3 and A3-bGFPD was cleaved by TEV protease for some SPR experiments.
Twin-Strep®-tagged proteins (bA3-2, eGFP and BFP) were also purified using a StrepTactin Sepharose affinity chromatography (StrepTrap™ HP 5 mL, GE Healthcare); both samples obtained from this first step purification were then submitted to a size exclusion chromatography.

All chemicals and reagents used for this work were purchased from Sigma‐Aldrich unless specified otherwise. E. coli BL21(DE3) Star competent cells were purchased from Themo Fisher Scientific and propagated in house. Anydrotetracycline was purchased from Cayman Chemical Company. StrepTrap HP 5 mL and HisTrap HP 1 mL columns were acquired from GE Healthcare. Nicotinamide adenine dinucleotide oxidized (NAD⁺) and reduced (NADH) forms were purchased from Apollo Scientific. Relisorb® EP400SS was donated by Resindion. Polyethyleneimine (PEI) (M_n=60000, 50 % aq. Solution, branched) was purchased from Acros Organics. 6‐Hydroxycaproic acid was purchased from Acros Organics. 5‐Aminovaleric acid and 4‐aminobutanoic acid were acquired from Apollo Scientific. 6‐Aminocaproic acid, ϵ‐caprolactone acid, and γ‐butyrolactone were purchased from Sigma. δ‐Valerolactone was acquired from Alfa Aesar. Commercial horse liver alcohol dehydrogenase was purchased from Sigma. Commercial immobilized CalB preparation (Novozym® 435) was acquired from Novozymes.