How did you calculate the concentration of oligo-HRP?

The protein concentration is determined by protein staining and oligo was calculated on OD260.

Is the “OD260nm/403nm value =1.1” in the data sheet appropriate? Because the molar extinction coefficient of oligo was 259500 mol-1Lcm-1, that is calculated by us, and HRP was 102000 mol-1Lcm-1, so theoretically the ratio of OD260nm/403nm should be = 2.5?

OD403 may be decrease for HRP during modification and conjugation. OD403 is not a sign of activity.

Any suggestions for ELISA with oligo-HRP?

Customer needs to titrate the experiments to find the best fit.