Term
| What is a coenzyme and what does it bind to? |
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Definition
Coenzyme - small molecules or metals that bind to proteins to make a functional enzyme
The protein they bind to is called the apoenzyme
Note: Neither the coenzyme or apoenzyme can catalyze a reaction alone. They must be paired to work |
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Term
| What are 4 advantages of enzymes |
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Definition
1. Increase reaction rates
2. Enable reactions under milder conditions
3. Increase reaction speificity
4. Enable regulation |
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Term
| How do enzymes increase reaction rates? |
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Definition
Then decrease the activation energy of a reaction.
Note: Enzymes do NOT affect Keq, but they make reactions reach equilibrium faster |
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Term
| What 2 aspects of a substrate determines is specificity for a particular enzyme |
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Definition
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Term
| What are the two mechanisms of a substrate binding to an enzyme? |
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Definition
1. Lock and key - specific substrate shape fits perfectly into active site of enzyme in a particular orientation
2. Induceable fit - enzyme doesnt have a specific shape to begin with but a substrate can induce a fit in the enzyme |
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Term
| In the Michaelis-Menten Equation, what does Km represent? |
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Definition
| The affinity of the enzyme for the substrate |
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Term
| What does Vmax depend on? |
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Definition
| [Et] (enzyme concentration) |
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Term
| What is Kcat and what does it represent |
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Definition
Kcat = Vmax/[Et]
Called the turnover number
Its a measure of the moles of product formed per mole of catalytic activity per unit time |
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Term
| What are some of the uses of enzyme kinetics? |
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Definition
1. estimate biological activity of an enzyme
2. Estimate cellular concentration of metablites
3. Assess enzyme activity in disease states
4. characterization of inhibitors (which many drugs are) |
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Term
| What enzymes are indicative of necrosis in a disease state for MI? What about liver damage? |
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Definition
MI - creatine phosphokinase, lactate dehydrogenase
Liver - Lactate dehydrogenase, alaine aminotransferase |
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Term
| What is an ELISA and what is it used for? |
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Definition
Enzyme-Linked Immunoassays
Coupling of antibodies specific for a protein antigen with an enzyme such that the complex allows detection of the antigen-antibody complex by a colored reaction
Used to diagnose diseases such as HIV |
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Term
| How can toxins and poisons affect enzymes? |
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Definition
Binding covalently to an enzyme resulting in its inhibition
Restoration of activity usually only occurs with synthesis of new enzyme |
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Term
| What type of reactions do oxidoreductases catalyze? |
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Definition
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Term
| What types of reactions do transferases catalyze? |
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Definition
Transfer reactions of functional groups between donors and acceptors
Note: Kinases are transferases the move phosphoate groups |
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Term
| What types of reactions do hydrolases catalyze? |
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Definition
| Hydrolytic reactions (cleavage by the addition of water) |
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Term
| What types of reactions do lyases catalyze? |
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Definition
| Addition or removal of water, ammonia, or carbon dioxide |
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Term
| What types of reactions do isomerases catalyze? |
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Definition
| Inversion of asymmetric carbons |
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Term
| What types of reactions do mutases catalyze? |
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Definition
| Intramolecular transfer of groups from one location in the substrate to another |
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Term
| What types of reactions do ligases catalyze? |
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Definition
The joining of two molecules with the consumption of ATP as an energy source
Notes:
1. Ligate means "to bind" (makes this easy to remember)
2. Ligases may also be called "Synthetases"
3. Ligases catalyze formation of tRNAs and synthesis of proteins <-- IMPORTANT FUNCTION |
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