Metabolism Flashcards
What is the simplest amino acid?
Glycine
What bonds combine to stabilise a protein?
Disulphide bridges, Hydrogen bonds, Ionic interactions, van der Waal’s, Hydrophobic interactions
In what direction is the polypeptide chain read?
From the N terminus to the C terminus
What two patterns can a beta-plated sheet form?
Parallel and Anti-parallel
What is the name given to proteins that help other proteins fold?
Chaperones
What is the name given to proteins that help other proteins fold?
Chaperones
How is glutamate important with regards to blood-clotting?
Gultamate is carboxylated to gamma-carboy-glutamate by Vitamin K-dependent carboxylase. The products is important in the blood-clotting cascade.
How does warfarin work?
It is an anticoaggulant that inhibits carboxylation of glutamate.
What does glucose-6-phosphatase do?
It is a liver enzyme that converts glucose-6p-phosphate into glucose, releasing glucose from stores of glycogen
What does glucose-6-phosphatase do?
It is a liver enzyme that converts glucose-6p-phosphate into glucose, releasing glucose from stores of glycogen.
What is Von Gierke’s disease?
Deficiency of glucose-6-phosphatase enzyme. Glucose cannot leave the liver. It results in low blood sugar levels, slow growth, hepatomegaly, and short stature.
What are the first two laws of thermodynamics?
1st: Energy cannot be created or destroyed
2nd: Entropy can only increase in an isolated system
What is Gibb’s Free Energy equation?
(delta)G = (delta)H - T(delta)S
With regards to Gibb’s Free Energy, when does a reaction spontaneously occur?
When (delta)G is negative?
What bond is often broken in ATP?
The phosphoanhydride bond.
How much energy is released when ATP is broken down into ADP and Pi?
-31 KJ/mol
What is the induced fit model?
Substate induces a change in conformation of the enzyme, which results in the formation of the active site.
What does lysozyme do?
Breaking the peptidoglycan layer of bacterial cell walls. Through hydrolysis of glycosidic bind between N-actetyl glucosamine (NAG) and N-acetyl muramic acid (NAM).
How does lysozyme work?
1) Glu35 pronates the oxygen in the glycosidic bond. breaking the bond.
2)
How does lysozyme work?
1) Glu35 pronates the oxygen in the glycosidic bond. breaking the bond. Asp52 stabilises the positive charge.
2) A water molecule enters and is de-protonated by Glu35, forming a hydroxide ion.
3) The hydroxide ion attacks the remaining sugar molecule adding an OH group.
What is the optimum pH of Lysozyme?
5.0 where Glu35 is unionised and Asp52 is ionised.
Where does glycolysis take place?
Cytoplasm
What are the first five steps of glycolysis?
1) Glucose + ATP -> Glucose-6-phosphate + H+ + ADP. By enzyme hexokinase.
2) Glucose-6-phosphate -> Fructose-6-phosphate. By enzyme phosphoglucose isomerase.
3) Fructose-6-phosphate + ATP -> Fructose-1,6-bisphosphate + ADP + H+. By enzyme phosphofructokinase
4) Fructose-1,6-bisphosphate -> Glyceraldehyde-3-phosphate + Dihydroxyacetone phosphate. By enzyme aldolase.
5) Dihydroxyacetone phosphate -> Glyceraldehyde-3-phosphate. By enzyme triose phosphate isomerase.
What are the last five steps of glycolysis?
6) 2X Glyceraldehyde-3-phosphate + Pi + NAD+ -> 2X 1,3-bisphosphoglycerate + NADH + H+. By enzyme glyceraldehyde-3-phosphate dehydrogenase.
7) 2X 1,3-bisphosphoglycerate +ADP -> 2X 3-phosphoglycerate + ATP. By enzyme phosphoglycerate kinase
8) 2X 3-phosphoglycerate -> 2X 2-phosphoglycerate. By enzyme phosphoglycerate mutase.
9) 2X 2-phosphoglycerate -> 2X Phosphoenolpyruvate + H20. By enzyme enolase.
10) 2X Phosphoenolpyruvate + ADP -> 2 X Pyruvate + ATP. By Pyruvate kinase.
What are the last five steps of glycolysis?
6) 2X Glyceraldehyde-3-phosphate + Pi + NAD+ -> 2X 1,3-bisphosphoglycerate + NADH + H+. By enzyme glyceraldehyde-3-phosphate dehydrogenase.
7) 2X 1,3-bisphosphoglycerate +ADP -> 2X 3-phosphoglycerate + ATP. By enzyme phosphoglycerate kinase
8) 2X 3-phosphoglycerate -> 2X 2-phosphoglycerate. By enzyme phosphoglycerate mutase.
9) 2X 2-phosphoglycerate -> 2X Phosphoenolpyruvate + H20. By enzyme enolase.
10) 2X Phosphoenolpyruvate + ADP -> 2 X Pyruvate + ATP. By Pyruvate kinase.
What is the difference between substrate level phosphorylation and oxidative phosphorylation?
Substrate level phosphorylation is the production of ATP by direct transfer of a high energy phosphate group. Oxidative phosphorylation is where ATP is produced using energy derived from electrons in an electron transport system.
What are the three possible fates of pyruvate?
1) Converted into lactate
2) Converted into ethanol
3) Converted into Acetyl-CoA
How is pyruvate converted into lactate?
Pyruvate + NADH + H+ -> Lactate + NAD+. By enzyme Lactate dehydrogenase.
How is pyruvate converted into ethanol?
1) Pyruvate + H+ -> acetaldehyde + CO2. By enzyme pyruvate decarboxylase.
2) Acetaldehyde + NADH + H+ -> Ethanol + NAD+. By enzyme alcohol dehydrogenase.
How is pyruvate converted into ethanol?
1) Pyruvate + H+ -> acetaldehyde + CO2. By enzyme pyruvate decarboxylase.
2) Acetaldehyde + NADH + H+ -> Ethanol + NAD+. By enzyme alcohol dehydrogenase.
What clinical significance does LDH (Lactate Dehydrogenase) have?
Elevated LDH levels can point to ischaemia, hepatitis, muscle injury, muscular dystrophy.
What does creatine kinase do?
Enzyme that catalyses the reaction:
Creatine phosphate + ADP -> Creatine + ATP
Where is pyruvate converted into acetyl-CoA?
In the mitochondria.
How is pyruvate converted into Acetyl-CoA?
Through the pyruvate dehydrogenase complex which catalyses:
Pyruvate + NAD+ +CoA -> Acteyl-CoA + CO2 + NADH + H+
What are the components of the pyruvate dehydrogenase complex?
Pyruvate decarboxylase with Thymine Pyrophosphate (TPP) prosthetic group.
Lipoamide reductase-transacetylase with Lipoamide prosthetic group.
Dihydrolipoyl dehydrogenase with FAD prosthetic group.
NAD+ and CoA co-factors.
How does the pyruvate dehydrogenase complex produce Acetyl-CoA?
Pyruvate
How does the pyruvate dehydrogenase complex produce Acetyl-CoA?
1) Pyruvate is decarboxylated with TPP forming Hydroxyethyl-TPP by enzyme Pyruvate Decarboxylase.
2) Hydroxyethyl-TPP is oxidised and transferred to Lipoamide (which replaces TPP) to become acetylipoamide. Catalysed by lipide reductase transacetylase.
3) Transfer of acetyl group to CoA to give actyl-coA, leaving a reduced lipoamide.
Why can acetyl CoA readily donate acetate to other molecules?
Thioester bond is highly energetic and is readily hydrolysed.
What are the first four steps in the TCA cycle?
1) Oxaloacetate + Acetyl-CoA -> Citrate + HS-CoA. By enzyme Citrate synthase.
2) Citrate -> Isocitrate. By enzyme aconitase.
3) Isocitrate + NAD+ -> (alpha)-ketogluterate + CO2 + NADH + H+. By enzyme isocitrate dehydrogenase
4) (alpha)-ketogluterate + HS-CoA + NAD+ -> Succinyl-CoA + CO2 + NADH + H+. By enzyme (alpha)-ketogluterate dehydrogenase complex.
What are the last four steps in the TCA cycle?
5) Succinyl-CoA + GDP + Pi -> Succinate + GTP + HS-CoA. By enzyme Succinyl-CoA synthetase.
6) Succinate + FAD -> Fumerate + FADH2. By enzyme succinate dehydrogenase.
7) Fumarate + H20 -> Malate. By enzyme fumarase.
8) Malate + NAD+ -> Oxaloacetate + NADH + H+. By malate dehydrogenase.
What does one turn of the TCA cycle produce?
2X CO2
3X NADH
1X FADH
1X GTP
Where does the Krebs Cycle take place?
The enzymes are in the mitochondrial matrix except for succinate dehydrogenase which is part of Cytochrome B-C1 complex.
Why can the Krebs Cycle only take place in aerobic conditions?
FADH2 and NADH need O2 to be re-oxidised.
Why can the Krebs Cycle only take place in aerobic conditions?
FADH2 and NADH need O2 to be re-oxidised.
How much ATP is produced per molecule of NADH and FADH2
NADH: 3 ATP
FADH: 2 ATP
How many ATP molecules is produced from one glucose molecule?
38
How are amino acids degraded?
Remove the main group (eventually excreted as urea) whilst the carbon skeleton is fed into the Krebs cycle or production of glucose.
