191- Immediately upon collection, gently invert collection tube five
times to mix blood. Be careful not to shake or treat the blood
violently in order to limit cell lysis. - Centrifuge blood at 2000 × g for 15–20 min, until plasma
separates. - Using a pipette, transfer all available plasma to a new tube for
protein digestion. Be careful not to disturb the cell layer inter-
face (see Note 2). - Add extracted plasma to a buffer solution.
- Add proteinase K to a concentration of 50–100 μg/mL.
- Incubate solution in an agitating water bath at 37–56 °C for
1 h to overnight. - [Optional] Incubate solution at 65 °C for 10 min to inactivate
proteinase K.
3.1.2 Proteinase K
Digestion
Fig. 1 Basic Method Schematic. This figure is a basic workflow schematic of the essential method, showing
each step and the basic reagents and conditions involved. Initial pipetting is represented by the pipette on the
first step, and by rounded arrows between tubes in following steps. ETOH ethanol
Cell-Free Plasma and Exosome-Associated DNA