{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Monday, October 19th, 2009

Monday, October 19th, 2009 - Monday October 19th 2009 I...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Lithotrophy A. Phototrophy B. Variation on basic ETS I. Recognizing that the hydrogenases that found in the lithotrophic bacteria are found membrane-associated = because they are membrane-associated, this dictates the electron flow = they oxidize hydrogen = 2e- + 2H+ = and the electrons are transferred to a quinone a. the litho part is not much of a problem = if the cell has generated NADH, that NADH can be oxidized by NADH dehydrogenases that pump protons = so that's the advantage of getting that proton pumps = the e- end up at a quinone and be oxidized by b/c complex = which pumps more protons = which reduces the cytochrome c = which can be oxidized by cytochrome oxidase = which can also pump protons - 1,3 bisphosphoglycerate ==NAD(P)H in, Pi out==> reduced to the aldehyde = glyceraldehyde-3-phosphate i. The problem is in the autotroph = 2e- + 2H+ + 2CO2 ===> CH2O - NADPH has a redox potential of E' = -320 mV - Q/QH2 has a redox potential E' = 0 mV - So we have electron in the quinone pool that is not electronegative enough to reduce NADPH = so energy has to be put in to the system to do that = this energy is called reverse electron transport - This is like pumping water uphill = it takes water to pump energy uphill = they have to use some conserve energy to do this = we have a high concentration of QH2/Q = the equilibirium has changed, there is a different equilibirum we can define = we can bring in protons from outside through the NADH dehydrogenase complex such that e- can be transferred from reduced quinone = quinol to NADPH = the cell must build up a membrane potential first = instead of bring those protons from the outside to make ATP, the protons can be utilize to make reverse e- flow = all lithotroph must carry this out = some of the phototroph must carry this out = it's all dictated by where the e- end up once the substrate has been oxidized - If there is a substrate from the outside and is oxidized at a particulate hydrogenase = the e- will end up as a quinol = therefore we must put energy into the system to get them to the level where they can be used to reduce CO2 because this is the reaction - It's not a problem converting NADH to NADPH there are enzymes that move the protons back and forth using membrane potential because NADPH is more electronegative than NADH, but it can be done - The big issue is getting it back to the reaction where it can occur - If they have used the soluble hydrogenase one, they wouldn't have to do that because the soluble hydrogenase generate NADH directly - The soluble hydrogenases are much more versitile metabolic = reduce NAD to NADH = why is this important? This really becomes important if it is a lithoautotroph b. So the big question is why do essentially all hydrooxidizing bacterial rely on a particulate
Background image of page 1

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

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 4

Monday, October 19th, 2009 - Monday October 19th 2009 I...

This preview shows document pages 1 - 2. Sign up to view the full document.

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