Enzymes as Biological Catalysts

Question 1

Enzymes play a central role in biology

Answer 1

1- carry out almost all chemistry required by living systems

2- permit a wide range of chemical reactions in a narrow set of conditions

3- allow rapid efficient adjustments to environmental conditions

Question 2

Medical Aspects of Enzymology

Answer 2

1- Diseases traceable to enzymatic defects
2- Use of enzyme activities in diagnosis
3- Drugs as enzyme inhibitors
4- therapeutic administration of enzymes
5- design of therapeutic enzymes and enzyme inhibitors

Question 3

General Characteristics of Enzymes

Answer 3

1- tremendous enhancement of reaction rate
2- reactions occur under relatively mild conditions
3- extreme specificity
4- capacity for regulation

Question 4

Enhancement of reaction rate

Answer 4

-enzymes often allow biological reactions to proceed at 10^6- 10^12 times the rate of the uncatalyzed reaction

Question 5

Reactions occur under Mild conditions

Answer 5

-only through the catalytic intervention of enzymes are some reactions able to occur under physiologically relevant conditions (i.e. physiological temperature, atmospheric pressure, aqueous solution, near neutral pH)

Question 6

Enzyme Extreme specificity

Answer 6

-enzymes must be extremely specific, both in identifying their substrates and in efficiently converting substrates to products with a minimum or errors, and in the very crowded environment of the cell

Question 7

Enzyme capacity for reguation

Answer 7

-catalytic activities of specific enzymes are highly regulated not only by varying the concentrations of enzyme and substrate, but also through allosteric control, covalent modifications, activation cascades, and other mechanisms

Question 8

Enzyme kinetics is an important tool in understanding enzyme mechanism and manipulating enzyme function

Answer 8

• protein structural information
• enzyme kinetics
• inhibition of enzyme activity
• enhancement of enzyme activity
• diagnostic tools
• design of activators, inhibitors, or improved enzymes
• mechanistic studies with different substrates, inhibitors

Question 9

Black box of enzymes

Answer 9

• we know what goes in and what comes out

- we can measure rate of substrate disappearance and product appearance

Question 10

Overview of an Enzyme Kinetics Experiment

Answer 10

1. Experiment- determine initial velocity of reaction at varied initial concentrations of substrate
2. Model- model what happens when enzyme converts substrate to product
3. Combine experimental data and model- interpret plot in terms of a model for enzyme behavior
4. Predict how an enzyme will behave under different conditions with kinetic constants- constants can be used to compare different enzymes or predict enzyme behavior under different conditions