Class Notes (808,126)
Canada (493,084)
BIOC13H3 (52)
Lecture 12

BIOC13H3 Lecture 12: BIOC13 Lecture 12

5 Pages
Unlock Document

University of Toronto Scarborough
Biological Sciences
Jason Brown

BIOC13 Lecture 12  Third step is to transfer thioester to coA from lipoic acid  Then you create acetyl coA, near equilibrium reaction because the energetics released is used to synthesize acetyl coA  Last 2 reactions are simply oxidation reactions, they serve to oxidize lipoic acid  Fad is similar to nad, can accept electrons from lipoic acid and becomes fadh2  Then nad comes in and steals electrons from fadh2  Electrons of pyruvate have made their way to nadh and carbons of pyruvate have ended up as co2  About 24-30 that form the outside of the compound  Then inside have 60 copies of E2 enzyme in center  Allows for substrate channeling when they are all sitting together  If they were separate enzymes then E1 does its reaction, produces intermediate, then that will have to diffuse and find the next enzyme and so on  Disadvantage is that the intermediates might get lost along the way  If you bring all theses enzymes then you get a much more efficient process  Substrate channeling where pyruvate comes in and the intermediates channel themselves from one channel to the next  Highly regulated enzymes are highly exergonic to make sure its not wasting energy  PD is highly regulated because it regulates the entry of carbs into the citric acid cycle  This is because we cant convert fats back into carbs, because no mechanism to convert acetyl coA back into pyruvate  When we run it through CAC, we have lost its potential to become something else  Lots of tissues rely on carbs as fuel source, such as brain  if short on carbs then we want to preserve pyruvate to make glucose  phosphorylating will inhibit the complex  activation via dephosphorylation  PDP1 and PDP2 and they work together  Both can be active at the same time, their job is to dephosphorylate  Major regulator is high levels of calcium and magnesium  High levels of calcium makes sense with muscle cells, when muscles are contracting, calcium gets released from sarcoplasmic reticulum and into the cytosol  Once it gets in mitochondria, it will lead to the ability to send pyruvate into citric acid cycle, which means you get a lot of ATP production for the muscle contraction  Calcium is linking muscle needs to a pathway that can produce lots of ATP  High levels of magnesium, it binds to ATP, but does not bind nearly as well to ADP  As we start breaking ATP into ADP, magnesium levels in cells start to rise because it’s not stuck to the ATP  Magnesium levels go up, as ATP levels go down  There are 4 versions of PDK for inhibition  PDK1 tends to get turned on when low levels of oxygen in the cells  When this happens, we would want the pyruvate to be fermented, rather than going through the process to become acetyl coa, which needs oxygen to be oxidized  pDK2 is activated by acetyl coA and NADH, if we have lots, why make more, so it can shut down the pathway  PDK3 is activated by ATP, if we have atp then no need for ATP  PDK4 turns on when we are starved or deprived of carbs, it will turn off pyruvate dehydrogenase complex, in order to do glucose sparring, to save the glucose to be used for brain and other tissues  Squirrel is hibernator, its chubby because its been eating nonstop to fatten up  All the increase in body mass is in fat, because fat is a better energy storage molecule  Going to live off the fat all winter long in underground nests  They have a huge amount of fat, there are some tissues in their body that cant use fats, like the brain so they will use glucose sparing, will make sure glucose isn’t used by tissues that can use fats, like the brain cant use fats  Muscle, heart, adipose can use fats so its highly expressed so they have glucose sparring  They reduce the oxidizing of pyruvate so that its available for brain  In pancreas, brain no expression of PDK4, or in kidney, testes  Those that need glucose need the pathway to be active, they don’t want glucose sparring  Liver doesn’t express PDK4, despite the fact that it can use fat  Liver is in glucose sparring, but it uses a different method  Glucagon signalling in liver leads to phosphorylation of and
More Less

Related notes for BIOC13H3

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.