explain what is going on in each figure. (DONT JUST SAY \"ETC\") i Preview File
ID: 216355 • Letter: E
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explain what is going on in each figure. (DONT JUST SAY "ETC")
i Preview File Edit View Go Tools Window Help )100% Mon Mar 26 2:39 PM a E cellandmolecularbiololgy-160422192843.pdf (page 219 of 837) Q Search BOOKMARKS 5.5 THE MACHINERY FOR ATP FORMATION 197 ADP P ATP ADP + ADP P ATP 0 ATP formation ADP P Spontaneous ATP formaionADP P at redcolored catalytic site ADP+ ADP + Pi 0 0 Ht ATP ADP P ATP FIGURE 5.27 The binding change mechanism for ATP synthesis. of additional protons induces a shift to the open (O) conformation, in (a) Schematic drawing showing changes in a single catalytic site during which the affinity for ATP is greatly decreased, allowing the product to acyele of catalysis. At the beginning of the cyele, the site is in the openbe released from the site. Once the ATP has dissociated, the catalytic site (O) conformation, and substrates ADP and P are entering the site. In is available for substrate binding, and the cycle is repeated. (b) Schematic step 1, the movement of protons through the membrane induces a shift drawing showing changes at all three catalytic sites of the enzyme to the loose (L) conformation in which the substrates are loosely bound imultaneously.The movement of protons through the Fo portion of the In step 2, the movement ofadditional protons induces a shift to the tight enzyme causes the rotation of the asymmetric ? subunit, which displays T) conformation, in which the affinity for substrates increases, causing three different faces to the catalytie subunits. As the y subunit rotates, it them to be tightly bound to the catalytic site. In step 3, the tightly bound induces changes in the conformation of the catalytic site of the B subunits ADP and P spontaneously condense to form a tightly bound ATP, no causing each catalytic site to pass successively through the T, O, and L change in conformation is required for this step. In step 4, the movement conformations. 26Explanation / Answer
Figure 1
The first diagram shows how a single catalytic site helps in the process of catalysis. At the start the site is in open conformation which allows entering of the APD + Pi. The O conformation shifts to L conformation due to the proton movement through membrane where substrates are attached. Gradually the conformation changes to T or tight conformation where it binds tightly to catalytic sites. During this the ATP changes to ADP and Pi and it forms tightly bound ATP and there is no change in the conformation. In the next step, it again moves or shifts to an open conformation and the ATP affinity decreases leading to release of the product. As the ATP moves, it opens the catalytic site for binding to the substrate. This figure shows how the catalytic site changes or how the conformation gradually changes. As the movement of protons takes place it causes the rotation of the gamma subunit and this induces a conformation change in the beta-subunit that rotates the catalytic from O to L to T to O conformation.
Figure 2
This is ATP synthase with two alpha, two beta and one gamma subunits where the beta-subunits are modified to contain 10 histidine residues at N-terminus and it is located on the outer face of F1 head. The gamma subunits are modified by replacing one of the serine residues near the end of the stalk with cysteine residues and it is attached to a fluorescent actin filament. It was observed that the actin filament moved during the presence of the ATP. This shows that for the movement of the actin filaments it requires the presence of ATP.
Figure 3
Proton diffusion in this is seen to be coupled to rotation of the c ring of the F0 complex and it is observed that each of the proton binds to the aspartic acid residue after it enters the half channel within the alpha-subunit from the intermembrane space. As the proton binds, it leads to a conformational change.
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