title: Conduction pathways in microtubules, biological quantum computation, and consciousness.
abstract: Technological computation is entering the quantum realm, focusing attention on biomolecular information processing systems such as proteins, as presaged by the work of Michael Conrad. Protein conformational dynamics and pharmacological evidence suggest that protein conformational states-fundamental information units ('bits') in biological systems-are governed by quantum events, and are thus perhaps akin to quantum bits ('qubits') as utilized in quantum computation. 'Real time' dynamic activities within cells are regulated by the cell cytoskeleton, particularly microtubules (MTs) which are cylindrical lattice polymers of the protein tubulin. Recent evidence shows signaling, communication and conductivity in MTs, and theoretical models have predicted both classical and quantum information processing in MTs. In this paper we show conduction pathways for electron mobility and possible quantum tunneling and superconductivity among aromatic amino acids in tubulins. The pathways within tubulin match helical patterns in the microtubule lattice structure, which lend themselves to topological quantum effects resistant to decoherence. The Penrose-Hameroff 'Orch OR' model of consciousness is reviewed as an example of the possible utility of quantum computation in MTs.
authors.affiliation: Department of Anesthesiology and Psychology, Center for Consciousness Studies, University of Arizona, Tucson, AZ 85721, USA. hameroff@u.arizona.edu
authors.forename: Stuart
authors.initials: S
authors.lastname: Hameroff
authors.forename: Alex
authors.initials: A
authors.lastname: Nip
authors.forename: Mitchell
authors.initials: M
authors.lastname: Porter
authors.forename: Jack
authors.initials: J
authors.lastname: Tuszynski
mesh_terms: D000758:Anesthesia; D003243:Consciousness; D049673:History, 20th Century; D006801:Humans; D008606:Mental Processes; D008870:Microtubules / Q000502:physiology*; D008954:Models, Biological; D008958:Models, Molecular; D009480:Neuropharmacology; D011487:Protein Conformation; D011789:Quantum Theory / Q000266:history; D015398:Signal Transduction; D014404:Tubulin / Q000737:chemistry / Q000502:physiology
chemical_list: D014404:Tubulin