Figure 2. (A) ─ A decrease of the biosensor signal for three oligomeric proteins immobilized on the optical chip СМ5 after injection of the acid buffer 10 mM Gly-HCl (pH 2.0): L-asparaginase from Erwinia chrysanthemi (ASP), human HIV1 protease (HIVp), human ferrochelatase (FECH). (B) ─ the biosensor signals of complex formation include by injecting 5 µM different protein analytes [NADPН-dependent adrenodoxin reductase (ADR), mothers against decapentaplegic homolog 4 (SMAD4), microsomal cytochrome b5 (СУВ5А)] via chip surface with immobilized ferrochelatase (FECH), as well as the complex formation between the immobilized bovine pancreatic trypsin (BPT) and peptide inhibitor of VG (InhVG) injected at a concentration of 8 µM. Samples of protein analytes were injected in the absence (control) or after short-term acid treatment (to pH 2.0) followed by subsequent neutralization to pH 7.4. Biosensor signals are shown as the mean values of the biosensor signals ± SD (n = 5). 1 RU (resonance unit) corresponds to 1 pg of protein bound to 1 mm2 of the chip surface.