Affinity-purified proteins were purified in the second step by gel filtration on ÄKTA Pure TM (Cytiva, USA) equipped with HiLoad 16/600 Superdex 75 pg column. After column equilibration with 50 mM phosphate buffer (pH 7.5), proteins were purified using the same buffer and concentrated on an Amicon® Ultra-15 Ultracel-10 gravity flow column 10K (Merck Milipore Ltd.).