The equal volume (100 uL) of 100% methanol and 62.5 uL of chloroform were added to 100 uL of soluble Protein and mixed well for 5 min. The sample was centrifuged at 12,000_ g for 15 min. The supernatant was removed without attaching the interface layer (protein fraction) by pipette. Then, 100 uL of 100% methanol was added to the sample and mixed gently for 5 min. The sample was centrifuged at 12,000_ g at 25 _C for 15 min. The supernatant was discarded, then the pellet was air-dried.