Preparation of a bio-immunoreagent between ZZ affibody and enhanced green fluorescent protein for immunofluorescence applications

In the present study, we constructed plasmid pUC-ZZ-EGFP to express Pro-ZZ-EGFP using ZZ peptide (a synthetic artificial IgG-Fc-fragment-binding protein derived from the B domain of staphylococcal protein A) and enhanced green fluorescent protein (EGFP). Without induction with isopropyl-β-d-thiogalactopyranoside, the chimeric protein was effectively expressed in Escherichia coli HB101. Its affinity constant binding IgG was 2.6 × 108 M−1 obtained by competitive enzyme-linked immunosorbent assay, indicating that the ZZ peptide retains the native structure in Pro-ZZ-EGFP. The application of immunofluorescence assay for detecting the Mycoplasma pneumoniae IgG antibody, Pro-ZZ-EGFP, exhibited a good signal comparable in brightness and fluorescence pattern with the signal generated using the fluorescein isothiocyanate-labeled anti-human IgG. The result indicates that Pro-ZZ-EGFP possesses great potential for clinical immunofluorescence IgG test as an alternative versatile fluorescent antibody.