Lect16-KR

Lect16-KR - Microbial energetics II October 6 2010...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Microbial energetics II October 6, 2010
Background image of page 1

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

View Full DocumentRight Arrow Icon
From Molecular Biology of the Cell , 4 th ed. Mechanical model of coupled biochemical reactions- harnessing the energy liberated from favorable reactions
Background image of page 2
If the electrons and protons from donors were given DIRECTLY to a terminal acceptor such as oxygen, a huge amount of energy would be released in an uncontrolled way, largely as unusable heat. Instead, bacteria perform several smaller electron transfers in sequence. This gives several places where the energy of a reaction can be converted into a proton gradient across the IM, which is another form of stored, usable energy.
Background image of page 3

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

View Full DocumentRight Arrow Icon
Characteristics of electron transport chains (regardless of exact proteins) 1) Contain protein complexes that span the cytoplasmic membrane (what would happen if these proteins floated in the cytoplasm?) 2) Electron carriers are arranged from lower to higher reduction potential ( E 0 ’) 3) Generate a proton motive force at sites of large Δ E 0 ´ 4) Start with a substrate oxidoreductase that receives electrons from NADH or an inorganic donor 5) Contain a pool of electron carriers that diffuse in the membrane to transfer electrons between protein complexes 6) End with a terminal oxidase that transfers electrons to the final electron acceptor
Background image of page 4
Proteins accept and donate electrons with the help of cofactors that are covalently or noncovalently bound to the protein In these reaction centers, the Fe atoms cycle between the 2+ and 3+ states as electrons are accepted and donated. Hemes can be covalently or noncovalently attached to the protein backbone. The reduction potential of each reaction center is determined by the number of Fe and S atoms in the cluster and/or the way that the cofactor is embedded in the protein.
Background image of page 5

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

View Full DocumentRight Arrow Icon
Flavin mononucleotide (FMN) is noncovalently bound to electron transport proteins. It can accept two protons and two electrons (two hydrogen atoms). The book says in one figure that H+ and e- from NADH end up on FMN in NADH dehydrogenase, but in the text it says that “each electron from NADH travels individually through FMN and the iron sulfur series.” It may not be known exactly what happens to the protons at this step.
Background image of page 6
Crystal structures show how cofactors are bound to proteins, and suggest how electrons are passed from one reaction center to another cytochrome c part of NADH dehydrogenase
Background image of page 7

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

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 22

Lect16-KR - Microbial energetics II October 6 2010...

This preview shows document pages 1 - 8. Sign up to view the full document.

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