Furthermore, the presence of these enzymes in the fermentation media may have deleterious effects on purification processes and antibody product quality. These effects were investigated for two purified monoclonal antibodies spiked into media containing varying concentrations of hydrolysates. Samples containing hydrolysates with significant proteolytic activity were shown to have much higher post-antibody peaks, increased leading shoulder, and more small clips by RP-HPLC than samples containing little to no enzyme activity. SE-HPLC also shows a post-antibody peak that may be the clipped antibody. Aside from the possible effects on antibody titer and quality, enzyme contamination could result in many purification problems downstream as well, such as the needed addition of another chromatography step to the purification process or shorter column lifetimes. These effects will also be discussed.