1 / 20

Lecture 5 Bioelectronics

Lecture 5 Bioelectronics. Nature’s transistors, rectifiers, capacitors ………. Current through your mitochondria. [O 2 ]. ADP. ADP. ADP. Time. Slope  current. The respiratory chain. The mitochondrial battery. Sugar. E (mV). -400. 0. +600.

snow
Download Presentation

Lecture 5 Bioelectronics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Lecture 5 Bioelectronics Nature’s transistors, rectifiers, capacitors ………..

  2. Current through your mitochondria [O2] ADP ADP ADP Time Slope  current

  3. The respiratory chain

  4. The mitochondrial battery Sugar E (mV) -400 0 +600 Drop in E across gaps is conserved as proton gradient for ATP synthesis O2+ 4H+ 2H2O

  5. Cytochrome c Oxidase An electron transfer-driven proton pump electrons H+ 5 metals ions 3 -redox centres CuA (Bi-nuclear Cu) Haem a Haem a3 - Cub Mitochondrialmembrane O2 + 4e- + 4H+ 2 H2O

  6. HQNO Protein based conducting pathways Formate Dehydrogenase

  7. Multielectron catalysts - molecular wires? Nitrite reductase NO2- + 10H+ + 8e- NH4+ + 2H2O Hydroxylamine oxidase NH2OH  HNO2 + 4H+ + 4e-

  8. Inspiration from Nature - molecular wires conducting in water 12nm

  9. Marcus Theory For non-adiabatic electron transfer between donor and acceptor separated by distance R. D-|A+ D|A kETis a function of: Distance between D and A Driving force

  10. Nature knows Marcus Theory Distance b ~ 1.4 Å-1 • Driving force • ~ 0.7 eV Page et al Nature (1998)

  11. A physicist’s current is a biochemists rate 1013s-1 = 1.6 µA 109s-1 = 0.16 nA 103s-1 = 0.16 fA Distance If b ~ 1.4 Å-1 then rate drops 10 fold every increase of 1.6Å between donor and acceptor

  12. _ _ + + Protein based conducting pathways - mobile carriers Interprotein electron transfer - the cytochrome c/cytochrome b5 paradigm • Stopped-flow kineticsOne of fastest known interprotein ET reactionsDiffusion limited at low I Still 108 M-1 s-1 at physiological I • Affinity measurements(by Spectrometry and potentiometry)Weak complex - KD 100µM at physiological I • Potential measurements at bulk equilibrium and by direct electrochemistry at surfacesCyt b5 redox potential goes up 40-80mV when bound to a positively charged surface

  13. Multihaem cytochromes - nature’s electrical contacts • React with solid metal oxides • Mobilisation of FeII from solid iron oxides • Reduction of soluble UVI to insoluble UIV oxides • Shewanella - 39 multihaem cytochome genes

  14. heterogeneous ET contact resistance 2D packing and interprotein ET + - Drain Source Surface attachment/localisation Bias application? Gating? A protein based transistor for nanotechnology?

  15. + - A biochemically gated transistor? Analyte

  16. Haem - a cofactor of choice 1.5nm • A conductor - cytochromes • A catalyst - P450’s • A carrier of dioxygen - globins • A sensor - for O2, CO, NO, oxidation state - globins, CooA, PAS etc

  17. COO- H3N+ COO- S S N N N N S S S S How do we connect electronically to proteins? Protein electrochemistry Needs functionalised surfaces - e.g. SAMs on gold, ‘Special’ Graphite Thiopyridine Small peptides

  18. AR NR AO NO Cytochrome c electrochemistry Electrochemically driven conformational change. i short timescale <100ms long timescale >1000s V Red Ox N-state His-Fe-Met +270mV A-state His-Fe-Lys -220mV

  19. 500bp – 170nm Electrochemistry and nanotechnology • AFM on DNA aligned proteins • Electrochemical AFM • Electrochemical STM • Test conductance of assembliese.g. two tip STM or patterned electrodes and conducting AFM tips

More Related