Quantum Biology - Meetup

1QUANTUM BIOLOGY

Richard Feynman:“Anyone who claims to understand quantum mechanicsis either lying or crazy”2Nevertheless .

3 The quantum world seems, despite many, manyexperiments to disprove it, to be the way theuniverse functions

Features of the Quantum World4 Particles can exist in multiple possible states or locationssimultaneously: “superposition”Unified particles which become separated remain connectedover distance and time: “quantum entanglement”Multiple particles can condense into one unified entity:“quantum coherence”Precise location AND momentum of quantum particle areindeterminate: “uncertainty”

5

Femtosecond6 A femtosecond is the SI unit of time equal to 10 15 of a secondFor context, a femtosecond is to a second what a second is to about 31.7 million years. A femtosecond is equal to 1000 attoseconds, or 1/1000 picosecond Typical time steps for molecular dynamics simulations are on the order of 1 fs. The waves of visible light oscillate with a period (reciprocal frequency) of about 2femtoseconds .The precise period depends on the energy of the photons, which determines their color 1.3 fs – cycle time for 390 nanometer light, at the transition between violet visible light and ultraviolet.2.57 fs – cycle time for 770 nanometer light, at the transition between red visible light and nearinfrared200 fs – the swiftest chemical reactions, such as the reaction of pigments in an eye to light.

What is Life?8 Erwin Schrödingerreasoned in 1944 thatquantum mechanics wasimportant in the stabilityof genetic information,and that quantumfluctuations might be thecause of some mutations.He arrived at thisconclusion on generalenergetic grounds.

HINTS OF QUANTUM PROCESSES ATWORK IN BIOLOGY9 More than the “trivial” quantum effects of atomicand molecular interactions, but deep involvement ofbiological processes

Mutations.10 Ever since Crick and Watson elucidated the structure of DNAthe possibility has been seriously entertained that mutationsmight occur as a result of quantum fluctuations, which wouldserve as a source of random biological information.Proton tunneling can indeed spontaneously alter thestructure of nucleotide bases, leading to incorrect pairbonding.McFadden and Al-Khalili have suggested that, in somecircumstances, the genetic code should be regarded as aquantum code, so that superpositions of coding states mightoccur, leading to spontaneous errors in base pairing

Tunneling11

Enzyme action.12 Enzymes are proteins. They catalyze biochemical reactions. But their hugely accelerated reactions rates, aredifficult to account for by conventional catalyticmechanisms.Evidence that quantum tunneling plays an essentialrole.

Genetic code.13 It has been argued that the code contains evidencefor optimization of a quantum search algorithm.The replication of DNA .This is accomplished by a DNA polymerase enzyme

Quantum Nanostructures.14 The living cell is a collection ofnanomachines that approach thequantum limit.Quantum electrodynamical effectsbecome significant.

Membrane proteins15 Another nanostructure of interest is the protonpumpAlthough these structures are complex enzymes, itmay be possible to model their operation as onedimensional quantum nanotubes.

Microtubules.16 Eccles argued that neuron firings are controlledby quantum tunneling processes at thesynapses.Hameroff and Penrose have suggested thatmicrotubules inside cells permit long-rangequantum coherence, enabling quantuminformation processing to take place at the subcellular level.They use this hypothesis to develop a theory ofconsciousness.

The Problem of Decoherence17 If quantum mechanics is to play a non-trivial role inbio-systems, then some way to sustain quantumcoherence at least for biochemically, if notbiologically, significant time scales must be found.The situation would be transformed, however, ifunexpectedly long decoherence times could bedemonstrated experimentally in a biological setting.

18

Water's quantum weirdness makeslife possible.19 The hydrogen bondingnetwork that is formedbetween molecules ofliquid water plays animportant role in thefunction of biologicalmolecules.The folding and functionof the proteins.

Coherent Control of ComplexSystems20 Do we live in a Quantum World?Quantum mechanics dictates that all matter has aninherent wave property.On a molecular scale, this property can lead todestructive and constructive interferences that havea pronounced effect on transmission probabilitiesalong reaction coordinates, for example the photoinduced isomerization of the retinal molecule inrhodopsins.

Myoglobin21

Myoglobin Secondary Structure22

23

The Environment of Action24 The vibrations of the surrounding protein areimportant.Simulation studies show that the vibrations ofcarboxy-hemoglobin must take surrounding proteinstructures into account to get qualitative agreementwith experimental results.

Photoreceptor Proteins,“Star Actors of Modern Times”25 Six well-characterized photoreceptor familiesfunction in Nature to mediate light-induced signaltransduction:the phototropins, andBLUF proteins.

Photosynthesis26 Photosynthetic light-harvesting proceeds by thecollection and highly efficient transfer of energythrough a network of pigment-protein complexes.Interchromophore electronic couplings andinteractions between pigments and the surroundingprotein determine energy levels of excitonic states,and dictate the mechanism of energy flow.

A quantum machine for efficientlight-energy harvesting.27

Fenna-Matthews-Olson complex28 The Fenna-Matthews-Olson(FMO) complex is a watersoluble complex and was thefirst pigment-protein complex(PPC) that has been structureanalyzed by x-rayspectroscopy

Redfield relaxation superoperator29 transfer between populations (blue), transferbetween coherences (green), and transfer betweena population and a coherence (red).

Direct evidence of quantum transport inphotosynthetic light-harvesting complexes.30 Evidence of interaction between thebacteriochlorophyll chromophores and the proteinenvironment surrounding them not only prolongsquantum coherence, but also spawns reversible,oscillatory energy transfer among excited states.Resolving design principles evident in this biologicalantenna could provide inspiration for new solarenergy applications.

31

The avian quantum compass.32

Flavin Adenine Dinucleotide (FAD)33 Flavin adenine dinucleotide (FAD) is a redox cofactor involved in severalimportant reactions in metabolism.FAD can exist in two different redox states, which it converts between byaccepting or donating electrons.The molecule consists of a riboflavin moiety (vitamin B2) bound to thephosphate group of an ADP molecule.FAD can be reduced to FADH2, whereby it accepts two hydrogen atoms (anet gain of two electrons):FAD is an aromatic ring system, whereas FADH2 is not. This means thatFADH2 is significantly higher in energy, without the stabilization thataromatic structure provides.FADH2 is an energy-carrying molecule, because, if it is oxidized, it willregain aromaticity and release all the energy represented by thisstabilization.

Magnetically sensitive light-inducedreactions in cryptochrome34Transient radical pairs (flavin-tryptopan) maybe formed by photo-induced electron transferreactions in cryptochrome proteins. Coherent spin dynamics are influenced by thegeomagnetic field leading to changes in thequantum yield of the signaling state of theprotein.

FAD35

36

Quantum Coherence Beating andPopulation Oscillation37

Could humans recognize odor byphonon assisted tunneling?39 Our sense of smell relies on sensitive, selectiveatomic-scale processes that occur when a scentmolecule meets specific receptors in the nose.The physical mechanisms of detection are unclear:odorant shape and size are important, butexperiment shows them insufficient.One novel proposal suggests receptors areactuated by inelastic electron tunneling from adonor to an acceptor mediated by the odorant, andprovides critical discrimination.

Vibrationally coherent photochemistry inthe femtosecond primary event of vision40 The observation of coherent vibrational motion ofthe photoproduct supports the idea that the primarystep in vision is a vibrationally coherent process andthat the high quantum yield of the cis-- transisomerization in rhodopsin is a consequence of theextreme speed of the excited-state torsional motion.

COQuantumNSCIClassicalOUSConsciousness is a process on the edge betweenquantum and classical worlds41

. However it takes time42

43

44

45

46

47

48

49

50

51

52

53

A closer look at the neural network54

55

56

57

58Tubulin Protein Proteins are made up ofamino acids.Some amino acids havering structures which arehydrophobic.Within this protein aremany locations where suchamino acids come togetherto form hydrophobicdomainsWithin such domainselectrons can formresonating structures

Some compounds that have an effect onconsciousness59

A bit of molecular biology60 Now we have seen microtubules in strategic placesin the brain and elsewhere.Microtubulin is a protein molecule that can exist ineither of two states.This is a necessary property for data storageHow is the information coded?The fundamental energy currency in biology is thehigh-energy phosphate bond.

Calciumcalmodulin kinase II (CaMKII)holoenzyme.61

“MEMORY BYTES” — MOLECULAR MATCH FOR CaMKIIPHOSPHORYLATION ENCODING OFMICROTUBULE LATTICES62 Learning, memory and long-term potentiation (LTP) aresupported by factors including post-synaptic calcium ion fluxactivating and transforming the hexagonalcalciumcalmodulin kinase II (CaMKII) holoenzyme.Upon calcium-induced activation, up to six kinase domainsextend upward, and up to six kinase domains extenddownward from the CaMKII association domain, the fullyactivated holoenzyme resembling a robotic insect 20nanometers in length.Each extended kinase domain can be phosphorylated, andable to phosphorylate other proteins, thus potentially furtherencoding synaptic information at intraneuronal molecularsites for memory storage, processing and distribution

63

Conclusions64 A better understanding of disease processes is possible.The deep problem of biogenesis – the discovery of apathway from non-life to life – may be advanced byviewing the origin of life not so much as a chemical process,but as the emergence of a specific, coded, informationprocessing system from an incoherent molecular milieu.A full account of biogenesis must address this softwareaspect.Advances in quantum information theory promise to cast thisproblem in an entirely new light, and could point the way tothe decisive breakthrough in explaining one of sciencesdeepest mysteries.

65Any Questions?AndThank you for yourattention.

References66 What is Life? Erwin Schrodinger, 1944Quantum biology, Nature Physics 9, 1018 (2013) doi:10.1038/nphys2474Quantum Biology: Current Status and /quantumbiology/report.phpOrchestrated Reduction Of Quantum Coherence In BrainMicrotubules: A Model For Consciousness?Stuart Hameroff & Roger Penrose, In: Toward a Science ofConsciousness - The First Tucson Discussions and Debates, eds.Hameroff, S.R., Kaszniak, A.W. and Scott, A.C., Cambridge,MA: MIT Press, pp. 507-540 (1996)The Miller Group, U. of T. Physics Department

Water's quantum weirdness makes life possible. 19 . Quantum Consciousness is a process on the edge between quantum and classical worlds Classical C . Advances in quantum information theory promise to cast this problem in an entirely new light, and could point the way to