To quantify the amount of HRP linked to each the activity was measured. The assay to probe the enzymatic activity of the HRP is based on measuring the oxidation rate of ethylbenzthiazoline-6-sulfonic acid) GABTs) in the presence of For the absorbance at 414 nm mea versus time was sured for all the samples. 1 mM of ABTs (Sigma Aldrich HA1888) solution in 50 mM dium phosphate, pH 6. was prepared. Also a solution of o.1 M H (Sigma Aldrich. #21676-3) in milli Q water
was prepared. The 25 puL of the H2O2 solution were added to 2.5 mL of the ABTS solution. Then. o 5 mL of this mixture was poured into a spectrophotometer cuvette together with 50 uL of the sample (either PC. first (wi) or last (w3) PC washes) and the changes in the absorbance at 414 nm were recorded using UVlvis absorption spectroscopy (Agilent 8453 UVIvis) (d. Fig. 3 and the supporting Information). A kinetic study was performed by continuous spectrophotometric rate determination (d. Fig. 3 and the Supporting Information). The activity rate k was determined by the value of the slope in the linear range of the measurement k AA 14/At- Then the activity rate, k Imin '1. was plotted versus the HRP concentration from o to 5 ug/mL (Fig. 3 and Supporting Information)