Term
| How big are enzymes compared to the substrates they act upon? |
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Definition
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Term
| Are enzyme reactions usually reversible? |
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Definition
| No, usually one reaction tends to proceed in a given direction regardless of substrate and product concentrations. |
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Term
| What are the types of reactions by which enzymes are catalyzed? |
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Definition
On The Higher Decks, Is Condensation
1) Oxidation/Reduction e.g. oxoreductase adds or removes a proton
2) Transfer of molecular groups-usually C, N, or P e.g. kinase
3) Hydrolytic Cleavage
4) Double bond alteration
5) Isomerization
6) Condensation |
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Term
| What does the apparent Km or Kapparent mean? |
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Definition
| K3 is not sufficiently small to say that the lower Km the greater the affinity of the enzyme and substrate for each other |
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Term
| What does Km equal when V is 1/2 Vmax? |
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Definition
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Term
| Why do we use a Lineweaver-Burk plot to find Vmax and Km? |
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Definition
| It is difficult to determine Vmax exactly as it approaches an asympototic limit. |
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Term
| Which form of hemoglobin is oxygenated? |
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Definition
| Relaxed form, some hydrogen bonds between alpha and beta dimers are broken in the oxygenated state |
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Term
| What type of hemoglobin is found in adults? |
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Definition
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Term
| What happens as more substrate binds to an allosteric enzyme? |
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Definition
Km decreases, which means increased affinity
V increases |
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Term
| What is an example of an allosteric enzyme in the eye? |
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Definition
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Term
| What type of plot allows us to determine Kapp for an allosteric enzyme? |
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Definition
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Term
| Why do we measure Kapparent with an allosteric enzyme? |
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Definition
| The K value of allosteric enzymes is dependent upon activators as well. |
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Term
| In which type of inhibition does the inhibitor replace or compete with the enzyme for the active site? |
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Definition
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Term
| In which type of inhibition does the inhibitor bind to a site close to the active site and prevents catalytic action on the substrate even though the substrate may bind to the enzyme. |
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Definition
| noncompetitive inhibition |
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Term
| In what type of inhibition are two substances usually required for catalytic action and the inhibitor binds to an area close to the active site after the substrate binds there. The inhibitor prevents the second substrate from ever binding. |
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Definition
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Term
| Name an example of uncompetitive inhibition in the eye. |
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Definition
| aldose reductase, an enzyme involved in cataract formation for people with diabetes or galactosemia |
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Term
| While most enzymes act intracellularly thus taking advantage of pH values that differ from physiololgic pH in the intercelluar fluid, give an example of an extracellular enzyme in th eye? |
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Definition
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Term
| Is lactate dehydrogenase and allosteric enzyme? |
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Definition
| No, although it has 4 subunits, the subunits do not interact |
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Term
| What do you call the phenomena of high lactate production coupled with high glucose and oxygen consumption? |
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Definition
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Term
What are two possible roles of aldose reductase? |
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Definition
1) oxidative prevention mechanism
2) osmotic regulator |
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Term
| How do polyols cause cataracts? |
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Definition
| Glucose and galactose are reduced with the help of aldose reductase to form sorbitol and galactitol. These polyols cannot exit the lens fiber cells. They increase in concentration, draw water in, and cause the lens fiber cells to burst. |
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