Why are microtubules candidates for biological quantum coherence?

"To summarize, cytoskeletal microtubules are likely candidates for quantum coherence relevant to consciousness because...

• Microtubule individual subunit (tubulin) conformations may be coupled to quantum-level events (electron movement, dipole, phonon) in hydrophobic protein regions.

• Microtubule paracrystalline lattice structure, symmetry, cylindrical configuration and parallel alignment promote long-range cooperativity and order.

• Hollow microtubule interiors appear capable of water-ordering, waveguide super-radiance and self-induced transparency."

  Stuart Hameroff,
  Quantum Coherence in Microtubules (1994)

Quantum coupled tubulin...

"The relevant particles in the brain are probably the electrons in the alpha-beta monomers boundary of the eight nanometer protein dimers on the surface of the microtubules in the living cell. These electrons are protected from thermalization because they are in hydrophobic volumes which are surrounded by ordered water and further protected by coherent electromagnetic fields inside the hollow microtubules. These electrons control the conformation of the dimer. They are quantum switches of a quantum computer. Coherent Frohlich piezo-electric waves propagate along the microtubule surface." Sarfatti

Microtubule paracrystalline lattice structure...

Hollow microtubule interiors...