Lectures 22 & 23 The TCA Cycle-BW

Nadh acetyl coa inhibit nad pyruvate coa activate 46

Info iconThis preview shows page 1. Sign up to view the full content.

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

Unformatted text preview: ibit NAD+, pyruvate, CoA activate 4/6 and 4/8/13 MCB 2000 Lectures 22 & 23 loss CO2 loss second CO2 molecule. Loss 2 CO2 molecules. 4 enxymes are regulated allosterically by AMP, ADP, and ATP. ADP stimulate isocitrate dehydrogenase - saying low ATP need to make ATP. ATP itself will inhibit isocitrate dehydrogenase allosterically when the rate is high. NADH and ATP indiicate the same thing both inhibit isocitrate dehydrogenase. energy charge is high. pruvate dehygroanse not part of the TCA or glycolysis - its the connceting link. How Is the TCA Cycle Regulated? Requirement for oxygen NO where did we consume molecule oxygen. - although this is dependent on oxygen. reason: electron accetor NAD+ to NADH that NADH must give up electrons to trasnport chain - fi nal electron acceoptor in the transport chain is oxygen. NADH will build up and feeback inhibit dehydrogenase (isocitrate) and slow it down. For regeneration of NAD+ and FAD-NADH and FAD(2H) are reoxidized in the electron transport chain where oxygen is the final electron acceptor. O xygen fi nal electron acceptor. -be able to accept electrons - so can r egenrate both elctron carriers. Rate of ATP utilization which is sensed by ATP/ADP/AMP levels Reduction state of NAD+ as reflected in the NADH/NAD+ ratio TCA regulated by energy charge itself - 4/6 and 4/8/13 MCB 2000 Lectures 22 & 23 Resting metabolic state - hgih atp and low adp - energy charge - NADH follows the same pattern - NAD+ low - high NADH. increase need for ATP - the ATP will be lower becuase being consumed in a pathway - ADP will rise - llow energy charge and low ATP to ADP r atio - ADP will dominate. 4/6 and 4/8/13 MCB 2000 Lectures 22 & 23 The Anabolic Role of the TCA Cycle 4/6 and 4/8/13 MCB 2000 Lectures 22 & 23 TCA intermediates are used in other pathways take off amino group of alanaine to get glucose. RBC always producing lactate acid - only doing glycolysis dont have mithcondria. WHen you form citrate in fed state - high citrate s ome of that citrate will cont in TCA cycle and some of it will diveraged - cirtrate exit mitchondria - cleave c irtrate back to acelty CoA and OAA - and actyl CoA back to fatty acid syntehzies. - building block for s tatured and unstartue fatty acid. OAA back to michondria. citrate syntehzie of fatty acids c holesterol - buildthat structure from 2 carbons of acetyl CoA - citrate is diverated in the fed state. Succinyl coA can make ring s turcutre of heme. - OAA ( oxloacetate) - why itis the rate liminting substrate - not just for citrate s yntahse. OAA can be converted to aspartic acid - adding amino group gives aspartatic acid - fasting when the liver has to carry out glucoglyensis - pryuvate will be dervice from alanaine or lactate acid - donig glucognesis - starting with pryuvate working way backwards to get glucose. Fig 20.17 4/6 and 4/8/13 MCB 2000 Lectures 22 & 23 Pyruvate Carboxylase can generate Oxaloacetate when TCA cycle intermediates are used in other reactions. Pyruvate carboxylase: Anapleurotic reaction both fed and fasted c onditions r efi llis the TCA c ycle to order r egenrate OAA Maintains TCA cycle Important in liver for gluconeogenesis 4/6 and 4/8/13 HOw is pryuvate coverted to OAA - enzyme that does this is pryuvate c arboxylase - pruvate 3 carbons need to get 4 carbons - so add a CO2 thats waht pruvate carboxylase does - adds CO2. pryuvate carboxylase enzyme that catylase an anapleuroti reaction - look back at the interamediate are used for other pathways - waht needs to happen? - pull off any of the intermediate to other pahtway - pull it off what has to happen? - have to replenish those intermeidate. anapleurotic reaction - fi ling up r eaction - fi lling up the TCA with the intermediates that have been consumed for other pahtways. way of replacing those intermediates. pryvuate c arobylase does exactly that MCB 2000 Lectures 22 & 23...
View Full Document

Ask a homework question - tutors are online