Macromolecular Crowding & Protein Folding

Real cytoplasm is not dilute buffer — it is packed with other proteins, RNA and sugars occupying 20–40% of the available volume. This simulator renders that crowded environment in 3D: translucent crowder spheres fill a box at a volume fraction you control, while a single protein chain drifts between an extended, unfolded coil and a compact, folded globule. The transition probability is not scripted — it comes from a real scaled-particle-theory excluded-volume free energy, combined with the protein's own intrinsic stability, updating live as you change crowder size, crowder density, chain length and intrinsic stability, with the resulting free energies, equilibrium constant and folded fraction shown as numeric readouts.