figure 2-3. table 2-2 figure 2-7 (1 of 3) figure 2-7 (2 of 3)
TRANSCRIPT
Figure 2-3
Table 2-2
Figure 2-7 (1 of 3)
Figure 2-7 (2 of 3)
Figure 2-7 (3 of 3)
Figure 2-8 (2 of 6)
Figure 2-8 (3 of 6)
Figure 2-8 (4 of 6)
Figure 2-8 (5 of 6)
Figure 2-8 (6 of 6)
Figure 2-9 (2 of 7)
Figure 2-9 (3 of 7)
Figure 2-11 - Overview (1 of 3)
Figure 2-14
Figure 2-15
METABOLISM
• Energy Transformations– What determines how much energy is transferred?
• What factors can influence whether a chemical reaction (or set of chemical reactions) produces a product?
• What is the difference between an exergonic and an endergonic reaction?
• What does it mean when reactions are coupled?
• Where does the energy to make ATP come from?
• Why do we make ATP (G= -30.9kJ/mole) rather than PEP (G=-60.9 kJ/mole)?
Compound Go'of phosphate hydrolysis (kJ/mol)
Phosphoenolpyruvate (PEP) - 61.9
Phosphocreatine - 43.1
Pyrophosphate - 33.5
ATP (to ADP) - 30.5
Glucose-6-phosphate - 13.8
Glycerol-3-phosphate - 9.2
High Energy Compounds
Gibbs Free Energy ChangesRxn#Enzyme ΔG°'(kJ/mol)
ΔG(kJ/mol)1 Hexokinase -16.7 -33.52 Phosglucoisom +1.7 -2.53 Phosfructkinase -14.2 -22.24 Aldolase +23.9 -1.35 TriosphosIsom +7.6 +2.56 G-3-PDH +12.6 -3.47 Phosglyc kinase -37.6 +2.68 Phosglyc mutas +8.8 +1.69 Enolase +3.4 -6.610 Pyruvate kinase -62.8 -33.4
1
2
3
4
5
6
7
8
9
10
ΔG°‘ = under standard temperature and pressure with equal concentrations of reactants
ΔG = non standardized conditions (physiological)
Figure 4-4 - Overview
Enzymes
• What kind of biomolecule is an enzyme?
• What does an enzyme do to make a reaction go faster?
• How do the substrates bind to the enzyme?
• What happens to the enzyme when the reaction is complete?
Figure 2-16
Figure 4-8
Table 4-3
Figure 2-17
Some Important Characteristics of Enzymes:
• Some enzymes must be “activated” before they can interact with their ligand
Figure 2-18
•Some require a cofactor or coenzyme in order to make the reaction proceed
Glucose +ATP Glucose-6-Phosphatehexokinase
Mg2+
Coenzyme
Coenzymes:
Pyruvate Lactate
Lactate dehydrogenase
NADH+ H+ NAD+
Table 2-3
Figure 2-19
Succinate FumarateSuccinate dehydrogenaseMalonate or oxaloacetate
FAD+ FADH2
Figure 2-20a
Glucose Glucose-6-phosphateATP ADP
Glycogen
Glycolysis
Glycogen phosphorylase
Figure 2-20b
Glucose Glucose-6-phosphateATP ADP
hexokinase
Covalent modulation – generally an addition or removal of a phosphate group; can either increase or decrease the activity of the enzyme
Triglyceride fatty acid + diglyceride Hormone sensitive
lipase
epinephrine
2nd messenger activation of kinase
P
Figure 2-21
Modulation by temperature
Modulation by pH –
How? What is the mechanism?
pH for Optimum Activity
EnzymepH
Optimum
Lipase (pancreas) 8.0
Lipase (stomach) 4.0 - 5.0
Lipase (castor oil) 4.7
Pepsin 1.5 - 1.6
Trypsin 7.8 - 8.7
Urease 7.0
Invertase 4.5
Maltase 6.1 - 6.8
Amylase (pancreas) 6.7 - 7.0
Amylase (malt) 4.6 - 5.2
Catalase 7.0
Figure 2-22
Enzyme
Given a set concentration of substrate, more enzyme makes a reaction proceed faster
Figure 2-23
enzyme
With a fixed concentration of enzyme, increasing the substrate concentration will lead to the enzyme becoming saturated, and the reaction will go no faster (maximum rate).
Many enzymes can bind more than one substrate. How can we tell which substrate binds more efficiently? Determine Km (binding affinity)!
*Rule = the smaller the Km, the tighter the binding
You have a mixture of several metabolic intermediates in a test tube. The intermediate compound A is the substrate of enzyme ZZ. Additional compounds include B, C, D, F, and G. Look at the following conditions and explain what is happening. Condition 1: A and B are in in the test tube in equal concentrations. A is found to occupy the active site 3X as often as B, but when both are present, the reaction rate slows down. Draw what the activity of the enzyme might look like in the presence of compound A, and then when A and B are both present. Condition 2: Enzyme ZZ is in the test tube with intermediates A, C and F. The activity of the enzyme is lower than expected. What is possibly happening and how would you determine whether your theory is true or not? Graph your experimental results.
Condition 3. Enzyme ZZ is in the test tube with intermediates B and D. The activity is higher than expected. What is possibly happening and how would you determine whether your theory is true or not? Graph your experimental results.
Activity of enzyme
[Substrate]
?