Fig. 3.
Effect of purification steps on protein yield and maleimide content. BSA was treated with 400-fold molar excess of the SM-(PEG)2. Excess linker was removed by either spin desalting column or dialysis (first purification). The protein yield and maleimide content of maleimide-BSA was determined by BCA (a) and modified Ellman’s test (b), respectively. The number of maleimides statistically decreased after overnight dialysis (**p < 0.01, T test). The combined effect of the two purification steps on protein yield was assessed by BCA (c). The yield of MorHap-BSA was significantly decreased in the second column purification (*p < 0.05, one-way ANOVA). Values are the mean of three independent experiments ± standard deviation