ATP Synthase - Molecular Biochemistry I F1Fo ATP Synthase...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
F 1 Fo ATP Synthase Copyright © 1999-2007 by Joyce J. Diwan. All rights reserved. Molecular Biochemistry I
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
F1Fo ATP Synthase of mitochondria, chloroplasts, bacteria: When the electrochemical H+ gradient is favorable, F1Fo catalyzes ATP synthesis coupled to spontaneous H+ flux toward the side of the membrane where F1 protrudes (e.g., toward the mitochondrial matrix). ADP + P i ATP F 1 F o 3 H + matrix intermembrane space ATP synthesis with pH & ∆Ψ - - - + + +
Background image of page 2
If no pH or ∆ Ψ exists to drive the forward reaction, K eq favors the reverse, ATP hydrolysis (ATPase). In some bacteria , the reverse reaction has a physiological role, providing a mechanism for ATP-dependent creation of a proton gradient that drives other reactions. ADP + P i ATP F 1 F o 3 H + ATPase with H + gradient dissipated matrix intermembrane space ADP + P i ATP F 1 F o 3 H + matrix intermembrane space ATP synthesis with pH & ∆Ψ - - - + + +
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Inhibitors of F1Fo, that block H+ transport coupled to ATP synthesis or hydrolysis, include: w oligomycin , an antibiotic w DCCD (dicyclohexylcarbodiimide), a reagent that reacts with carboxyl groups in hydrophobic environments, forming a covalent adduct.
Background image of page 4
Roles of major subunits were determined in studies of submitochondrial particles ( SMP ). In mitochondria treated with ultrasound , inner membrane breaks & reseals as vesicles, with F1 on the outer surface. Since F1 of intact mitochondria faces the matrix, these SMP are said to be inside out . By EM with negative stain, ATP Synthase appeared as " lollipops " on the inner mitochondrial membrane, facing the matrix. Higher resolution cryo-EM later showed each lollipop to have 2 stalks . See Movie. mitochondrion ultrasound SMP F 1
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
w After removal of F1 , the SMP membrane containing Fo is leaky to H+ . Adding back F1 restores normal low permeability to H+. Thus it was established that Fo includes a “ H+ channel ." w F1 , the lollipop head , when extracted from SMP, catalyzes ATP hydrolysis (spontaneous reaction in the absence of an energy input). Thus F1 contains the catalytic domain(s). mitochondrion ultrasound SMP F 1
Background image of page 6
w Either oligomycin or DCCD blocks the H+ leak in membranes depleted of F 1 . Thus oligomycin & DCCD inhibit the ATP Synthase by interacting with Fo . ATP synthase complexes of bacteria, mitochondria & chloroplasts are very similar, with only minor differences. ADP + P i ATP F 1 F o 3 H + matrix intermembrane space ATP synthesis with pH & ∆Ψ - - - + + +
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
are believed to have evolved from symbiotic aerobic bacteria ingested by an anaerobic host cell. The limiting membrane of the bacterium became the inner mitochondrial membrane . Mitochondria contain a small DNA chromosome, but genes that encode most mitochondrial proteins are in the nucleus, consistent with transfer of some DNA during evolution. aerobic
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/25/2010 for the course BCH 4024 taught by Professor Allison during the Spring '08 term at University of Florida.

Page1 / 35

ATP Synthase - Molecular Biochemistry I F1Fo ATP Synthase...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online