Two variants of the
Treponema pallidum
membrane protein A (TmpA-His, and TmpA) were expressed in
Escherichia coli
W3110 strain. TmpA-His was cloned with a six histidine tag at the
C-terminus and was purified by immobilized metal ion affinity chromatography (IMAC). For this purpose, Sepharose 4B-IDA was used as matrix, and Ni
2+
and Cu
2+ as chelating metal ions. Using this rapid and single-step chromatography the initial 20% purity of TmpA-His reached 90%. The overall yield was 70% and the binding capacity of the matrix for TmpA-His was approximately 1 mg/mL. TmpA was purified by electroelution and the yield was estimated to be 1 mg per each electroelution. The use of both proteins in the diagnosis of syphilis was evaluated by ELISA using panels of positive and negative sera. With respect to the serologic performance no differences between both proteins were found, which suggests the potential use of TmpA-His in the development of diagnostic systems for syphilis serodiagnosis.