DOWNSTREAM BIOPROCESS OPTIMIZATION OF BOVINE GAMMA GLOBULIN AS A PROTEIN MODEL FOR THE PREPARATION OF F(AB’)2

Abstract

This work was aimed to study pH and temperature effects on the digestion process of IgG to F(ab’)2. Experiments were designed with 2 factors and 2 levels of each factor, and bovine gamma globulin was used as a protein model. Purification process of F(ab’)2 was performed by using centrifugal filtration. Purity and secondary structure of F(ab’)2 after digestion and purification process were evaluated by size exclusion chromatography (SEC) and circular dichroism (CD) spectroscopy, respectively. Results of the study showed that: (a) pH has more effect on the digestion process than does a temperature, (b) centrifugal filtration with a molecular weight cut off (MWCO) at 30K could yield F(ab’)2 with a purity up to 89%, as determined by SEC, and (c) it could be estimated from CD measurement of F(ab’)2 that its secondary structure comprise parallel β 32.6%, antiparallel β 44.7%, α-Helix 0.0% and other structure 22.7%.