Final Flashcards
Enzymes regulated by BOTH ATP/ADP
Inhibited by High ATP
PFK-1, Pyruvate Kinase, PDComplex, Isocitrate Dehydrogenase
Enzymes only INHIBITED by high ADP
Pyruvate Carboxylase, PEPCK
ATP has no effect
Activation step for Glycogen Synthesis
1 UTP + G-1-P –> UDP-Glucose (During Fed State!)
By udp-glucose-pyrophosphatase
Activation step for FAS
ACC - Adds CO2 + ATP to Acetyl CoA to make Malonyl CoA (Fed State)
Activation step for Cholesterol Synthesis
(Not rate limiting step)
Making Isoprene Unit = 3 ATP + Mevalonate –> 3-Isopentenyl Pyrophosphate (Fed State)
Activation step for Phospholipid synthesis
CTP + Polar Head group or DAG (Fed State)
Activation step for Triglyceride synthesis
Sike! there is none
Activation steps for Gluconeogenesis
6 ATP/GTP, during various regulation steps - Energy Source = beta-oxidation of FAs (Fasted state)
Activation step for FA oxidation (Beta oxidation)
Fatty Acid chain + Acyl (not acetyl) CoA + ATP –> FattyAcid-CoA (Driven by pyrophosphate hydrolysis)
Processes during fed state
Glycolysis, PDC, Glycogen synthesis, FA synthesis, Cholesterol Synthesis
Processes during fasted state
Ketogenesis, Gluconeogenesis, Glycogen degradation, FA oxidation
Rate Limiting step for Cholesterol Synthesis
HMG CoA Reductase:
HMG-CoA –> Mevalonate
Requires 2 NADPH
Rate Limiting Step for Fatty Acid Synthesis
Acetyl CoA Carboxylase:
Acetyl CoA + CO2 + ATP –> Malonyl CoA
All Carboxylases require ______ as coenzyme
Biotin
Rate Limiting step for Glycolysis
PFK1
F-6-P –> F-1,6-BP
Rate Limiting Step for TCA Cycle
Isocitrate Dehydrogenase:
Isocitrate + NAD+ –> alpha-ketoglutarate + CO2
Rate Limiting Step for Gluconeogenesis
F-1,6-Bisphosphatase
F-1,6-BP –> F-6-P
Reactions in mitochondria
FA oxidation
PDC (Acetyl CoA Production)
TCA Cycle
Oxidative phosphorylation
Both mito + cytosol:
Gluconeogenesis
Reactions in Cytoplasm
Glycolysis
FA Synthesis
Cholesterol Synthesis
Both:
GNG
Structure of cholesterol
three 6 membered, one 5 membered
Acetone must be exhaled because ketone body production leads blood pH to ______
Decrease – Acidosis
TCA Cycle Regulated by
[Acetyl CoA] and [OAA], ATP utilization, O2, NAD+/NADH
Muscle Contraction effects:
TCA cycle increases, O2 consumption increases, ADP increases, H+ gradient decreases (ox. phos. increases to restore H+ Gradient)
Insulin receptor cascade
NO G Protein
Binds –> IRS-1 phos. –> PI-3-Kinase phos. –> PIP2 phos. to PIP3 –> PDK-1 phos. –> AKT phos
GPCR Oxytocin
G protein activated –> Alpha subunit activates PLC –> PIP2 cleaved to IP3 and DAG –> IP3 releases CA2+ –> Ca2+ and DAG activate PKC
GPCR Epi/Glucagon
G-alpha activates adenylate cyclase –> cAMP produced –> cAMP activates PKA
RTK: RAS/RAF
GRB2 –> Sos –> Ras –> Raf –> Mek –> Erk1/2 –> Other shit
Do insulin receptors dimerize?
They don’t need to, they are always dimerized
Substrate level phosphorylation
Creatine phosphate, 1,3-BPG from step 6 glycolysis, PEP from step 10 glycolysis
Hexokinase/Glucokinase
Glucokinase (high Km) = Liver
Hexokinase = brain, all other tissues
Trap Glucose within cell to commit it to glycolysis
TCA Cycle intermediates are used in other pathways:
Citrate –> FAs, sterols
Alpha-ketoglutarate –> Glutamate –> Other amino acids –> Purines
Succinyl CoA –> porphyrins/heme
Oxaloacetate –> Aspartate -> Purines/Pyrimidines
OAA –> Glucose via GNG
Glucokinase regulation
Not FBI, inducible by insulin
Hexokinase regulation
FBI by G-6-P (product)
PFK-1 regulation
No hormonal
+: AMP, F-2,6-P (Not product F-1,6-P)
-: Citrate, ATP
PFK-2 regulation
Normal hormonal fed state active (NHFedSA)
Pyruvate Kinase
High energy charge inhibition (HECI), normal hormonal fed state active (NHFedSA)
PDH Complex
Pyruvate + NAD+ + CoA –> Acetyl CoA + CO2 + NADH + H+
PDH Complex regulation
High energy charge inhibition (HECI),
+: ADP, NAD+, Pyruvate
-: ATP, NADH, Acetyl CoA
NHFedSA
Is there hormonal regulation in the TCA Cycle?
NO! There is no I/G effect on TCA Cycle
Isocitrate dehydrogenase regulation
HECI (ATP/ADP),
+: NAD+
-: NADH
Alpha-ketoglutarate dehydrogenase regulation
HECI,
+: NAD+
-: NADH, Succinyl CoA
Which enzymes reduce NAD+ in TCA cycle?
All the dehydrogenases
Glycogen synthase
UDP-Glucose to alpha-1,4 linkages
Glycogen synthase regulation
Activated by G-6-P and dephosphorylated+activated by Protein Phosphatase 1,
NHFedSA!
NHFSA (Normal hormonal fed state active enzymes)
PFK-2, Pyruvate Kinase, PDH Complex, Glycogen synthase, ACC, HMG-CoA Reductase,
Glycogen Phosphorylase regulation
Protein phosphorylase dephosphorylates and inactivates, Opposite of NHFSA, it is active when phosphorylated
Acetyl CoA Carboxylase regulation
Citrate attaches to polymerize/activate, palmitoyl attaches to inactivate by depolymerization, NHFSA Inactivated by AMP-Kinases Inhibited by ADP HECA HECA
Pyruvate carboxylase
Pyruvate to OAA for FAS
Pyruvate carboxylase regulation
Acetyl CoA positive allosteric
Activated by High Energy Charge (HECA!)
PEPCK function + Regulation
OAA to PEP - phosphorylate and decarboxylate
Inhibited only by high ADP
FBPase 2 function + regulation
against PFK2 to break down F-2,6-P, Opposite of NHFedSA, it is active when phosphorylated
Part of 2 part enzyme, other half is PFK2
Glucose-6-Phosphatase location, function
Removes phosphate from G-6-P
Only exists in liver so glucose –> Blood!
G-6-P in muscle goes right to glycolysis
Lactate Dehydrogenase function and regulation
Anaerobic respiration.. Pyruvate + NADH –> Lactate + NAD+
More NADH = positive
Less NADH = negative
Oxygen present?
Cholesterol made where?
Liver
Requirements for cholesterol synthesis
Acetyl CoA - thioester bonds
ATP
NADPH
O2
Mnemonic for Cholesterol
Alcoholic’s Anonymous Has Me Insane and Dying, I’D Go For Some Sweet PinaColada Laced Cocaine
LDL receptors undergo ___
Receptor mediated endocytosis
LDL receptors if mutated
LDL production will increase abnormally
Statin Drugs which step interfers
HMG-CoA Reductase
Competitive inhibitors!
HMG-CoA Reductase regulation
Phosphorylation by AMPKinases, HECA
Degradation - half life is 3 hrs - if Cholesterol is HIGH
Transcription/Translation by SCAP, SREBP, SRE - ONLY IF Cholesterol is LOW
SCAP SREBP SRE mechanism
SCAP and SREBP on membrane, if low cholesterol detected, they go into a golgi and go to nucleus where SREBP binds to SRE on chromosome and activates production of HMG-CoA
HDL
Reverse cholesterol transport- brings back cholesterol from vascular tissue to return to lver
Trans fat vs Saturated fat
Trans fat lowers HDL and raises LDL. Saturated Fat raises LDL but ignores HDL
Are there glucagon receptors in muscle?
No, only the liver responds to I/G ratio
Glycogen phosphorylase cleaves glycogen at the _________ ends
non-reducing ends
Transferase in glycogen degradation
transfers 3 glucoses before a branch point to the non-reducing end of a 1,4 linkage