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Figure 6.1 The complexity of metabolism

Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

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Page 1: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.1  The complexity of metabolism

Page 2: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Page 3: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.6  Energy changes in exergonic and endergonic reactions

Page 4: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.7 Disequilibrium and work in closed and open systems

Page 5: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.8 The structure and hydrolysis of ATP

Page 6: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.9  Energy coupling by phosphate transfer

Page 7: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.10 The ATP cycle

Page 8: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.11 Example of an enzyme-catalyzed reaction: Hydrolysis of sucrose

Page 9: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.12 Energy profile of an exergonic reaction

http://www.stolaf.edu/people/giannini/flashanimat/enzymes/transition%20state.swf

Page 10: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.13 Enzymes lower the barrier of activation energy

Page 11: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.14 The induced fit between an enzyme and its substrate

Page 12: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.15 The catalytic cycle of an enzyme

Page 13: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.16 Environmental factors affecting enzyme activity

Page 14: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Characterizing enzymes

• Vmax - rate when enzyme is saturated with substrate

• KM – substrate concentration that allows reaction to proceed at 1/2 Vmax

• KM – useful as a measure of how tightly an enzyme binds its substrate– Low KM means tight binding, high KM

means weak binding

• Enzyme kinetics

Page 15: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Characterizing enzymes

• Turnover number: Vmax/enzyme concen.

– typically about 1000 substrate molecules processed per second per enzyme molecule, but can be much higher

Page 16: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Enzyme Turnover number (per second)

Carbonic anhydrase 600,000

Acetycholinesterase 25,000

Amylase 18,000

Penicillinase 2,000

DNA Polymerase 15

Page 17: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Measuring enzyme activity

• One unit of an enzyme is defined as the amount that will catalyze a defined amount of substrate in one minute under specified conditions.

• For catalase:

one unit decomposes 1mole H2O2 at 250C at pH 7.

Page 18: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

What to measure for rate?

• Amount of substrate used over a specified time.

OR

• Amount of product accumulated over a specified time.

• Which to use???

Page 19: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.17 Inhibition of enzyme activity

Page 20: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.18 Allosteric regulation of enzyme activity

Page 21: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.19 Feedback inhibition

Page 22: Figure 6.1 The complexity of metabolism. Figure 6.5 The relationship of free energy to stability, work capacity, and spontaneous change

Figure 6.20 Cooperativity