10. Kevin Ahern's Biochemistry - Enzymes II
- Duration: 50:48
- Updated: 22 Oct 2013
1. Contact me at kgahern@davincipress.com / Friend me on Facebook (kevin.g.ahern)
2. Download my free biochemistry book at http://biochem.science.oregonstate.edu/biochemistry-free-and-easy
3. Take my free iTunes U course at https://itunes.apple.com/us/course/biochemistry/id556410409
4. Check out my free book for pre-meds at http://biochem.science.oregonstate.edu/biochemistry-free-and-easy
5. Course video channel at http://www.youtube.com/user/oharow/videos?view=1
6. Check out all of my free workshops at http://www.youtube.com/playlist?list=PLlnFrNM93wqyTiCLZKehU1Tp8rNmnOWYB&feature;=view_all
7. Check out my Metabolic Melodies at http://www.davincipress.com/metabmelodies.html
8. My courses can be taken for credit (wherever you live) via OSU's ecampus. For details, see http://ecampus.oregonstate.edu/soc/ecatalog/ecourselist.htm?termcode=all&subject;=BB
9. Course materials at http://oregonstate.edu/instruct/bb450
Highlights Enzymes II
1. Km is the substrate concentration that gives Vmax/2. Vmax varies, depending on the amount of enzyme that one uses, but Km is a constant for a given enzyme.
2. The higher the Km of an enzyme, the LOWER its affinity for its substrate and conversely, a low Km is consistent with a high affinity of enzyme for substrate.
3. If one lets a reaction go for a long time, it will reach equilibrium. At equilibrium, the relative concentration of products and reactants do not change. Initial velocities of reactions are therefore measured so as to avoid allow the product to accumulate and favor the reverse reaction.
4. Lineweaver-Burk plots are alternative plots of V vs S data obtained by taking the inverse of each and plotting it, thus making a 1/V vs 1/[S] plot.
5. On a Lineweaver-Burk plot, the Y intercept is 1/Vmax and the X intercept is -1/Km.
6. The catalytic actions of enzymes are related to their ability to be flexible. Fischer proposed a model of catalysis called the Lock and Key model, describing enzymes as inflexible and the substrate as like a key fitting into a lock.
7. Koshland's Induced Fit model says that not only does the enzyme change the substrate, but the substrate also changes the enzyme shape upon binding. This transient change of enzyme shape is important for catalysis because it may bring together molecular groups that may not be close together in the enzyme prior to the change in enzyme shape.
8. Chemical changes brought about by catalysis facilitate a change in enzyme shape to allow for the release of products. When this happens, the enzyme returns to its original shape.
9. "Perfect" enzymes are enzymes that have evolved to the point where any additional mutation will reduce their ability to catalyze reactions. They are not common. Perfect enzymes have a very high ratio of Kcat/K. The only thing that inhibits their ability to function more efficiently is the rate of diffusion of substrate in water.
10. The active site of an enzyme is the place in the enzyme where a reaction is catalyzed. A substrate is a molecule bound by an enzyme and acted upon it.
11. Sequential Displacement has two subsets.
a. Random binding - the order of binding multiple substrates is not rigidly set.
b. Ordered binding - Simple ordered binding - one substrate binds first followed by another followed by release of product.
12. Another non-covalent enzyme mechanism involving multiple substrates is called Double Displacement (or Ping-Pong). In this method, the enzyme only binds one substrate at a time, but switches back and forth between different states.
13. Allosterism occurs when a small molecule interacts with a protein and affects its activity.
14. Enzymatic reactions can be inhibited by reversible and irreversible processes. Reversible processes involve binding of an inhibitor and its subsequent release. Irreversible processes involve covalent attachment of a molecule to an enzyme.
a. Competitive Inhibition - Occurs when the inhibitor competes with the substrate for the binding site on an enzyme. The greater the concentration of inhibitor, the greater the inhibition. Competitive inhibition can be overcome by increasing amounts of substrate. The apparent Vmax of competitive inhibition does not vary from the Vmax of the same reaction when uninhibited. The apparent Km, however, does vary.
b. Non-competitive inhibition - This type of reversible inhibition occurs when an inhibitor binds to an enzyme at a site unrelated to the substrate binding site. In this case, the inhibitor's binding to the enzyme is unrelated to the binding of the substrate and the inhibitor does not have to have a structure like that of the substrate. Thus, the inhibitor and substrate don't compete with each other. The inhibitor can inhibit the enzyme (during its binding) without interference from the substrate. Therefore, increasing substrate concentrations cannot eliminate the effect of the inhibitor. In this case, the Vmax is lowered, but the Km is unchanged.
http://wn.com/10._Kevin_Ahern's_Biochemistry_-_Enzymes_II
1. Contact me at kgahern@davincipress.com / Friend me on Facebook (kevin.g.ahern)
2. Download my free biochemistry book at http://biochem.science.oregonstate.edu/biochemistry-free-and-easy
3. Take my free iTunes U course at https://itunes.apple.com/us/course/biochemistry/id556410409
4. Check out my free book for pre-meds at http://biochem.science.oregonstate.edu/biochemistry-free-and-easy
5. Course video channel at http://www.youtube.com/user/oharow/videos?view=1
6. Check out all of my free workshops at http://www.youtube.com/playlist?list=PLlnFrNM93wqyTiCLZKehU1Tp8rNmnOWYB&feature;=view_all
7. Check out my Metabolic Melodies at http://www.davincipress.com/metabmelodies.html
8. My courses can be taken for credit (wherever you live) via OSU's ecampus. For details, see http://ecampus.oregonstate.edu/soc/ecatalog/ecourselist.htm?termcode=all&subject;=BB
9. Course materials at http://oregonstate.edu/instruct/bb450
Highlights Enzymes II
1. Km is the substrate concentration that gives Vmax/2. Vmax varies, depending on the amount of enzyme that one uses, but Km is a constant for a given enzyme.
2. The higher the Km of an enzyme, the LOWER its affinity for its substrate and conversely, a low Km is consistent with a high affinity of enzyme for substrate.
3. If one lets a reaction go for a long time, it will reach equilibrium. At equilibrium, the relative concentration of products and reactants do not change. Initial velocities of reactions are therefore measured so as to avoid allow the product to accumulate and favor the reverse reaction.
4. Lineweaver-Burk plots are alternative plots of V vs S data obtained by taking the inverse of each and plotting it, thus making a 1/V vs 1/[S] plot.
5. On a Lineweaver-Burk plot, the Y intercept is 1/Vmax and the X intercept is -1/Km.
6. The catalytic actions of enzymes are related to their ability to be flexible. Fischer proposed a model of catalysis called the Lock and Key model, describing enzymes as inflexible and the substrate as like a key fitting into a lock.
7. Koshland's Induced Fit model says that not only does the enzyme change the substrate, but the substrate also changes the enzyme shape upon binding. This transient change of enzyme shape is important for catalysis because it may bring together molecular groups that may not be close together in the enzyme prior to the change in enzyme shape.
8. Chemical changes brought about by catalysis facilitate a change in enzyme shape to allow for the release of products. When this happens, the enzyme returns to its original shape.
9. "Perfect" enzymes are enzymes that have evolved to the point where any additional mutation will reduce their ability to catalyze reactions. They are not common. Perfect enzymes have a very high ratio of Kcat/K. The only thing that inhibits their ability to function more efficiently is the rate of diffusion of substrate in water.
10. The active site of an enzyme is the place in the enzyme where a reaction is catalyzed. A substrate is a molecule bound by an enzyme and acted upon it.
11. Sequential Displacement has two subsets.
a. Random binding - the order of binding multiple substrates is not rigidly set.
b. Ordered binding - Simple ordered binding - one substrate binds first followed by another followed by release of product.
12. Another non-covalent enzyme mechanism involving multiple substrates is called Double Displacement (or Ping-Pong). In this method, the enzyme only binds one substrate at a time, but switches back and forth between different states.
13. Allosterism occurs when a small molecule interacts with a protein and affects its activity.
14. Enzymatic reactions can be inhibited by reversible and irreversible processes. Reversible processes involve binding of an inhibitor and its subsequent release. Irreversible processes involve covalent attachment of a molecule to an enzyme.
a. Competitive Inhibition - Occurs when the inhibitor competes with the substrate for the binding site on an enzyme. The greater the concentration of inhibitor, the greater the inhibition. Competitive inhibition can be overcome by increasing amounts of substrate. The apparent Vmax of competitive inhibition does not vary from the Vmax of the same reaction when uninhibited. The apparent Km, however, does vary.
b. Non-competitive inhibition - This type of reversible inhibition occurs when an inhibitor binds to an enzyme at a site unrelated to the substrate binding site. In this case, the inhibitor's binding to the enzyme is unrelated to the binding of the substrate and the inhibitor does not have to have a structure like that of the substrate. Thus, the inhibitor and substrate don't compete with each other. The inhibitor can inhibit the enzyme (during its binding) without interference from the substrate. Therefore, increasing substrate concentrations cannot eliminate the effect of the inhibitor. In this case, the Vmax is lowered, but the Km is unchanged.
- published: 22 Oct 2013
- views: 5079