Preparing cell-free systems involves isolating the desired enzymes from their natural sources, which could be bacteria, yeast, or other organisms. Techniques such as centrifugation, chromatography, and electrophoresis are commonly used for enzyme purification. Once isolated, enzymes are mixed in a controlled environment with the necessary cofactors and substrates to initiate the catalytic reaction. Advanced cell-free systems may also involve genetic engineering to produce modified enzymes with improved catalytic properties.