figure 2-3. table 2-2 figure 2-7 (1 of 3) figure 2-7 (2 of 3)

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]

?