Microbial Physiology notes lec17 11-3-10

Microbial Physiology notes lec17 11-3-10 - Microbial Physio...

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Microbial Physio Lecture 17: F-ATPases: A Rotary Motor continued November 3, 2010 1. F 1 segment that can be easily isolated free of the integral membrane constituents because it separates out into the soluble fraction after being treated w/ detergents 2. they took the F 1 which contain the alpha, beta, gamma, delta, and epsilon subunits they tagged the subunits w/ poly-histidine tags and they anchored the subunits to a solid support so they created a solid matrix underneath the subunits to which the poly-histidine tags on the subunits would bind 3. But then how are you going to measure the rotation of the gamma subunit if it does occur?? a. They covalently linked a biotin to the end of the gamma subunit, and distal to the alpha and beta subunits i. Gamma subunit is in the middle of the alpha beta ring, and the biotin(avidin) is stuck to the gamma on top, and then to be able to see the gamma subunit if it does rotate, the scientist attached a big actin fiber pole to the avidin 1. and the did see the actin fiber rotate, therefore the gamma subunit was rotating ii. Biotin contains the protein avidin which is highly toxic because it binds biotin, so if you have too much avidin in system, it can kill you because it forms a complex w/ biotin in your body and then you cant perform decarboxylation rxn which are biotin dependent 4. remember that in the rotor it is comprised of the c subunit, and the gamma and epsilon subunits w/in the membrane of the cell a. the rotor is what moves/rotates the rotation of the rotor is mediated by the influx of protons across the cell membrane b. the stator which is made up of the a, b, delta, alpha, and beta subunits stay stationary as the transport of protons across the cell membrane occurs Bacterial Rhodopsin Light-driven proton pump
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1. Bacterial rhodopsin is a retinal binding protein a. It is a 7 transmembrane alpha helix structure that traverses the plasma membrane 7 times w/ 7 long alpha helices b. The 7 alpha helices surrounds the retinal(long unsaturated hydrocarbon chain) the retinal is parallel to the plane of the membrane, and it is covalently bound to the K216 in the middle of the 7 th helix in rhodopsin
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This note was uploaded on 01/09/2011 for the course BIMM 130 taught by Professor Saier during the Fall '10 term at UCSD.

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Microbial Physiology notes lec17 11-3-10 - Microbial Physio...

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