PROTEIN PHYSICSPROTEIN PHYSICS

LECTURE 12LECTURE 12

GlobularGlobular

FibrousFibrous

H-bondsH-bonds & & hydrophobicshydrophobics

MembraneMembrane

________

membranemembrane

BacteriorodopsinBacteriorodopsinwith retinalwith retinal

Transport of protons HTransport of protons H++

PorinPorinTransport of polar moleculesTransport of polar molecules

Pore in membrane.Pore in membrane.Free energy of charge in the non-polar pore:Free energy of charge in the non-polar pore:

~ q~ q2 2 // [( [(MEMBRMEMBR WATERWATER ) )1/21/2 rrPOREPORE] ~ ] ~

~ 20 kcal/mol ~ 20 kcal/mol / / rrPOREPORE((ÅÅ))

G-proteinG-protein

Slow decay of GTP = timer of actionSlow decay of GTP = timer of action

Photo-Photo-syntheticsyntheticcentercenter

PigmentsPigmentsin photo-in photo-syntheticsyntheticcenter:center:ElectronElectrontransfertransfer

chlorophyllchlorophyll

LightLight

TunnelingTunneling

P(X) ~ 10P(X) ~ 10-X(-X(Å)Å)

T-independentT-independentFrequency of Frequency of vibrations (attacks):vibrations (attacks):f ~ 10f ~ 101515/sec/secSuccessful attacks:Successful attacks:ffSUCCSSUCCS..(x)(x) ~ P(x)•f~ P(x)•f,, e.g.: e.g.:

ffSUCCSSUCCS..(5Å)(5Å) ~ 10~ 10-5+15 -5+15 ~ ~

~ 10~ 101010/sec/sec

Atom Atom 1 1Å Å Attenuation of Attenuation of electron density: electron density: