Extended Data Fig. 9: Production and purification of recombinant proteins used in LOCKR biosensor for serological diagnosis of neutralizing antibodies.
a, Individual His6 tagged versions of lucKey (27.4 KDa) and lucCageRBD (47.8 KDa) are expressed in E. coli and following cell lysis are purified by IMAC using 50 mM imidazole in buffer elution. b, His6 tagged SARS-CoV-2 RBD (30 KDa) is expressed as a secreted protein in human 293 cells transiently transfected with DNA vectors encoding the protein which is purified from serum free culture medium by IMAC using 50 mM imidazole in buffer elution. c, His6 tagged LCB1 anti-SARS-CoV-2 RBD minibinder (7 KDa) is expressed in E. coli (whole cell). Following cell lysis by heating to 95 °C and centrifugation to separate insoluble from soluble material, the LCB1 minibinder protein is >90% pure. Samples shown in A-C were analyzed by SDS-PAGE with reducing agent and Coomassie blue staining (molecular weight standards shown). All experiments were performed in triplicate, representative data are shown.
