Denaturation of Serum Proteins Thaw serum from −70°C freezer immediately before serum fractionation. Aliquot 20 µL of serum to each well in a 96-well sample plate. Add 30 µL of D1 denaturing buffer to the well containing the serum to denature the serum proteins. Shake the sample plate on a Micromix 5-01 shaker vigorously (in an amplitude of 7 and form of 20 Hg) for 20 min at 4°C to mix the serum with the D1 buffer well.