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Lecture 1- Metabolism: Basic Concepts and Design. Chem 454: Regulatory Mechanisms in Biochemistry University of Wisconsin-Eau Claire. Introduction. Questions we will focus on this semester: How does a cell extract energy and reducing power from its environment? - PowerPoint PPT Presentation
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Chem 454: Regulatory Mechanisms in Biochemistry
University of Wisconsin-Eau Claire
Chem 454: Regulatory Mechanisms in Biochemistry
University of Wisconsin-Eau Claire
Lecture 1- Metabolism: Basic Concepts and Design
Lecture 1- Metabolism: Basic Concepts and Design
22
Questions we will focus on this semester:
How does a cell extract energy and reducing power from its environment?
How does a cell synthesize the building blocks of its macromolecules and the then the macromolecules themselves?
How are these processes integrated and regulated?
Questions we will focus on this semester:
How does a cell extract energy and reducing power from its environment?
How does a cell synthesize the building blocks of its macromolecules and the then the macromolecules themselves?
How are these processes integrated and regulated?
IntroductionIntroduction
33
Living organisms require an input of free energy to meet various needs:
For mechanical work
For active transport of molecules and ions
For synthesis of biomolecules
Living organisms require an input of free energy to meet various needs:
For mechanical work
For active transport of molecules and ions
For synthesis of biomolecules
IntroductionIntroduction
44
Living organisms require an input of free energy
Phototrophs
Use energy from the sun to convert energy-poor molecules into energy rich molecules
Chemotrophs
Obtain energy by oxidizing the energy-rich molecules made by the phototrophs
Living organisms require an input of free energy
Phototrophs
Use energy from the sun to convert energy-poor molecules into energy rich molecules
Chemotrophs
Obtain energy by oxidizing the energy-rich molecules made by the phototrophs
IntroductionIntroduction
55
Reduced molecules are energy-richOxidized molecules are energy-poor
Reduced molecules are energy-richOxidized molecules are energy-poor
IntroductionIntroduction
66
Energy from photosynthesis or the oxidation of fuels can be transformed into an unequal distribution of ions across a biological membrane.
The ion gradient can be used for
Oxidative phosphorylation to make ATP
Active transport across membranes
Nerve transmission
Energy from photosynthesis or the oxidation of fuels can be transformed into an unequal distribution of ions across a biological membrane.
The ion gradient can be used for
Oxidative phosphorylation to make ATP
Active transport across membranes
Nerve transmission
IntroductionIntroduction
77
Ion gradients:Ion gradients:
IntroductionsIntroductions
See Chapter 2.3.3See Chapter 2.3.3
88
Metabolism is composed of many coupled interconnecting reactions
Metabolism is composed of many coupled interconnecting reactions
MetabolismMetabolism
99
MetabolismMetabolism
1010
Classes of metabolic pathways:Catabolic pathwaysThose that convert energy into biologically useful
forms
Anabolic pathwaysThose that require an input of energy
Classes of metabolic pathways:Catabolic pathwaysThose that convert energy into biologically useful
forms
Anabolic pathwaysThose that require an input of energy
MetabolismMetabolism
1111
Basic concepts of metabolism include:
Thermodynamically unfavorable reactions can be driven by favorable reactions.
ATP is the universal currency of free energy.
ATP hydrolysis drives metabolism by shifting the equilibrium constant of coupled reactions.
There is a structural basis for the high phosphoryl transfer potential of ATP.
The phosphoryl transfer potential is an important form of cellular energy transformation.
Basic concepts of metabolism include:
Thermodynamically unfavorable reactions can be driven by favorable reactions.
ATP is the universal currency of free energy.
ATP hydrolysis drives metabolism by shifting the equilibrium constant of coupled reactions.
There is a structural basis for the high phosphoryl transfer potential of ATP.
The phosphoryl transfer potential is an important form of cellular energy transformation.
MetabolismMetabolism
1212
Thermodynamically unfavorable reactions can be driven by favorable reactions.Free energy change for a reactions:
Thermodynamically unfavorable reactions can be driven by favorable reactions.Free energy change for a reactions:
ThermodynamicsThermodynamics
1313
Coupling unfavorable reactions with favorable ones
Coupling unfavorable reactions with favorable ones
ThermodyamicsThermodyamics
1414
ATP is the universal currency of free energy
ATP is the universal currency of free energy
ATPATP
1515
Hydrolysis of ATP:Hydrolysis of ATP:
ATPATP
1616
ATP hydrolysis drives metabolism by shifting the equilibrium of coupled reactions
ATP hydrolysis drives metabolism by shifting the equilibrium of coupled reactions
ATP HydrolysisATP Hydrolysis
1717
Problem:Under standard conditions, the free energy
for the hydrolysis of L-glycerol phosphate to form glycerol and inorganic phosphate is -2.2 kcal/mol. Calculate the factor by which the equilibrium ratio for the concentration of L-glycerol phosphate to glycerol is increased when ATP is used as the phosphoryl donor for the formation L-glycerol phosphate in place of inorganic phosphate.
Problem:Under standard conditions, the free energy
for the hydrolysis of L-glycerol phosphate to form glycerol and inorganic phosphate is -2.2 kcal/mol. Calculate the factor by which the equilibrium ratio for the concentration of L-glycerol phosphate to glycerol is increased when ATP is used as the phosphoryl donor for the formation L-glycerol phosphate in place of inorganic phosphate.
ATP Hydrolysis ATP Hydrolysis
Do this calculation for liver where the concentrations for ATP, ADP and Pi are 3.5 mM, 1.8 mM and 5.0 mM, respectively.
Do this calculation for liver where the concentrations for ATP, ADP and Pi are 3.5 mM, 1.8 mM and 5.0 mM, respectively.
1818
Phosphoryl transfer is a common means of energy coupling
Molecular motors
Muscle contraction
Ion pumps
Phosphoryl transfer is a common means of energy coupling
Molecular motors
Muscle contraction
Ion pumps
ATP HydrolysisATP Hydrolysis
1919
Structural basis for high transfer potentialCompare:
Structural basis for high transfer potentialCompare:
Phosphoryl TransferPhosphoryl Transfer
2020
Phosphate ester vs Phosphate anhydride
Phosphate ester vs Phosphate anhydride
Phosphoryl TransferPhosphoryl Transfer
2121
Stabilization of orthophosphate
resonance stabilization
electrostatic repulsion
hydration
Stabilization of orthophosphate
resonance stabilization
electrostatic repulsion
hydration
Phosphoryl TransferPhosphoryl Transfer
2222
Resonance stabilizationResonance stabilization
Stabilization of OrthophosphateStabilization of Orthophosphate
OrthophosphateOrthophosphate
PyrophosphatePyrophosphate
2323
There are other molelcules with favorable phosphoryl transferase energies
There are other molelcules with favorable phosphoryl transferase energies
Phosphoryl Transfer and Energy Transfer
Phosphoryl Transfer and Energy Transfer
2424
In terms of energy for phosphoryl transfer, ATP is intermediate:
In terms of energy for phosphoryl transfer, ATP is intermediate:
Phosphoryl TransferPhosphoryl Transfer
2525
Question:What information do the ∆Go’ data given in
Table 14.1 provide about the relative rates of hydrolysis of pyrophospate and acetyl phosphate?
Question:What information do the ∆Go’ data given in
Table 14.1 provide about the relative rates of hydrolysis of pyrophospate and acetyl phosphate?
Phosphoryl TransferPhosphoryl Transfer
2626
Creatine phosphate is used to generate ATP in the short term:
Creatine phosphate is used to generate ATP in the short term:
Phosphoryl TransferPhosphoryl Transfer
2727
The oxidation of Carbon fuels is an important source of cellular energy
The oxidation of Carbon fuels is an important source of cellular energy
Cellular EnergyCellular Energy
2828
The oxidation of Carbon fuels is an important source of cellular energy
The oxidation of Carbon fuels is an important source of cellular energy
Cellular EnergyCellular Energy
2929
High phosphoryl transfer potential compounds can couple carbon oxidation to ATP synthesis.Ion gradients across membranes provide an important form of cellular energyThe extraction of energy from foodstuffs occurs in stages.
High phosphoryl transfer potential compounds can couple carbon oxidation to ATP synthesis.Ion gradients across membranes provide an important form of cellular energyThe extraction of energy from foodstuffs occurs in stages.
Cellular EnergyCellular Energy
3030
High phosphoryl transfer potential compounds can couple carbon oxidation to ATP synthesis.
Example from glycolysis:
High phosphoryl transfer potential compounds can couple carbon oxidation to ATP synthesis.
Example from glycolysis:
Coupling oxidation to ATP synthesisCoupling oxidation to ATP synthesis
3131
In the next step ATP is harvested from the high energy phosphate intermediate.
In the next step ATP is harvested from the high energy phosphate intermediate.
Coupling oxidation to ATP synthesisCoupling oxidation to ATP synthesis
3232
Ion gradients across membranes provide an important form of cellular energy
Ion gradients across membranes provide an important form of cellular energy
Ion GradientsIon Gradients
3333
Ion gradients across membranes can be used to synthesize ATP
Ion gradients across membranes can be used to synthesize ATP
Cellular EnergyCellular Energy
3434
Extraction of energy from foodstuffs is carried out in stages:
Extraction of energy from foodstuffs is carried out in stages:
Cellular EnergyCellular Energy
3535
Activated carriers exemplify the modular design and economy of metabolism.
Key reactions are reiterated throughout metabolism.
Metabolic processes are regulated in three principle way.
Activated carriers exemplify the modular design and economy of metabolism.
Key reactions are reiterated throughout metabolism.
Metabolic processes are regulated in three principle way.
Recurring Motifs in MetabolismRecurring Motifs in Metabolism
3636
ATP is an activated carrier of phosphate groups
Other examples include:
Activated carriers of electrons in oxidation reactions
Activated carriers of electrons in reductive biosynthesis
Activated carriers of two-carbon fragments
ATP is an activated carrier of phosphate groups
Other examples include:
Activated carriers of electrons in oxidation reactions
Activated carriers of electrons in reductive biosynthesis
Activated carriers of two-carbon fragments
Activated CarriersActivated Carriers
3737
NAD+
(Nicotinamide Adenine Dinucleotide)
NAD+
(Nicotinamide Adenine Dinucleotide)
Activated carriers of electrons in catabolism
Activated carriers of electrons in catabolism
3838
FAD(Flavin Adenine Dinucleotide)
FAD(Flavin Adenine Dinucleotide)
Activated carriers of electrons in catabolism
Activated carriers of electrons in catabolism
3939
Reduction of isoalloxazine ring of FADReduction of isoalloxazine ring of FAD
Activated carriers of electrons in catabolism
Activated carriers of electrons in catabolism
4040
NADPH(Nicotinamide Adenine Dinucleotide Phosphate)
NADPH(Nicotinamide Adenine Dinucleotide Phosphate)
Activated carriers of electrons in biosynthesis
Activated carriers of electrons in biosynthesis
4141
Coenzyme A is a carrier of Acyl groups
Coenzyme A is a carrier of Acyl groups
Activated carriers of acyl groupsActivated carriers of acyl groups
4242
Other common activated carriers:Other common activated carriers:
Activated CarriersActivated Carriers
4343
There are six basic reactions in metabolism:There are six basic reactions in metabolism:
Key ReactionsKey Reactions
4444
Metabolic motifsMetabolic motifs
Key ReactionsKey Reactions
4545
Metabolic processes are regulated in different ways:
Enzyme levels
Enzyme activity
Accessiblity of substrates to the enzyme
Metabolic processes are regulated in different ways:
Enzyme levels
Enzyme activity
Accessiblity of substrates to the enzyme
Metabolic RegulationMetabolic Regulation
4646
Degradative and biosynthesis pathways are usually distinct
Compartmentalization
Allosteric control
Degradative and biosynthesis pathways are usually distinct
Compartmentalization
Allosteric control
Metabolic RegulationMetabolic Regulation
4747
The energy chargeThe energy charge
Metabolic RegulationMetabolic Regulation
4848
The structures
of ATP,
CoEnzyme A
NADH and FADH2 belie
their “RNA
world” origin.
The structures
of ATP,
CoEnzyme A
NADH and FADH2 belie
their “RNA
world” origin.
Evolution of Metabolic Pathways
Evolution of Metabolic Pathways
4949
The pK of an acid is measure of its proton-group-transfer potentiala. Derive a relation between ΔGo’ and pK.b.What is the ΔGo’ for the ionization of
acetic acid, which has a pK of 4.8?
The pK of an acid is measure of its proton-group-transfer potentiala. Derive a relation between ΔGo’ and pK.b.What is the ΔGo’ for the ionization of
acetic acid, which has a pK of 4.8?
ProblemsProblems
5050
Calculate ΔGo’ for the isomerization of glucose 6-phosphate to glucose 1-phosphate. What is the equilibrium ration of glucose 6-phosphate to glucose 1-phosphate at 25°C?
Calculate ΔGo’ for the isomerization of glucose 6-phosphate to glucose 1-phosphate. What is the equilibrium ration of glucose 6-phosphate to glucose 1-phosphate at 25°C?
ProblemsProblems