Question

8. a) Calculate the ATP yield for myristic acid, 14:0. Don't forget the cost of activation. (8 pts) b) What are the ATP yields from NADH and FADHz if the c collar of the Fo section of F1Fg-ATPase has 15 subunits? Show work. (6 pts) 9. Write out a reasonable mechanism for the ligase-catalyzed reaction below. (6 pts) + CASH+ AMP + PP: op die

Answer 1

8. a) ATP from myristic acid oxidation:

• Step-1 (activation)

myristic acid to myristoyl CoA =  - 2ATP

• Further steps:

7 acetyl CoA

As per acetyl CoA, 12 ATP's are generated = 7 * 12 = 84 ATPs

6 oxidation cycles

6 NADH - as for 1 NADH, 3 ATP's are generated. Therefore, 6 * 3 = 18 ATP

6 FADH2 - as for 1 FADH2, 2 ATP's are generated. Therefore, 6 * 2 = 12 ATP.

So, total ATP's generated = 84 + 18 + 12 = 114 ATP

Subtracting the ATP's spent during activation, net yield is 114 - 2 = 112 ATPs.

b) Normally, c collar of the Fo subunit of F0-F1 ATPase has 10 subunits. Only one out of these c subunits can form a bond with a subunit at a time, due to which the ring rotates one-tenth of a turn of the adjacent a subunit.

As one NADH gave electrons to complex I (at higher energy level), it generated 3 ATP's during the ETC.

and similarly as FADH₂ gave electrons to complex II, it generated 2 ATP's through ETC.

F0-F1 ATPase complex is shown as below:

B A α 8 B B α ATP b2 ADP + Pi N side Υ E RUN scuri US a C10 p00000 P side H+

^{Image adapted from https://www.slideserve.com/vlad/fig19-16}

Roughly, 8 protons enter the mitochondria through the F0 subunit for every 3 ATP synthesized.

That means around 2.67 protons for each ATP.

The no. of protons generated by the NADH and FADH2 are independent of the change in the c units of the F0 subunit and hence, there will likely not be any change in the no. of ATP synthesized from NADH or FADH₂.