Here we provide our pipeline for antibody discovery process. Starting from de novo isolation from custom made phage display libraries to expression and downstream applications; it allows us to obtain recombinant antibodies with desired properties to vast set of antigens. We also developed the CYB5-fusion system for periplasmic expression of multimeric proteins with the possibility of process monitoring. The combination of redox dependent absorbance spectrum of red-colored cytochrome b5 with its high value molar extinction coefficient allows us to monitor antibody fusion proteins localization, redox state and quantify them in reliable way in turbid solutions. Moreover, it was revealed that due to outstanding stability and solubility, cytochrome b5 significantly enhances expression level of antibody fragments in Escherichia coli periplasm.