Block 1 - MBOD - 8/31/06
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- What is an essential component of energy usage and metabolism?
- ATP
- ATP's production linked to the _________ of food.
- oxidation
- What is NAD?
- Niacin
- What is another name for what NAD serves as?
- Enzyme Cofactor
- When NAD is reduced you get what?
- NADH
- What is NAD involved in primarily?
- Electron transport chain
- What is produced via the ETC?
- ATP
- What is the name of another version of NAD that has a phosphate added, and what is this other compounds primary function?
- NADP is the compound, and its primary involvement is as a reducing agent, which means it gets oxidized
- What else is NADP involved in?
- It is involved in biosynthesis
- FAD is what?
- Another important compound that gets reduced
- NAD and FAD have adenine and sugar ________ connections.
- ribose
- What does FAD do?
- It is a compound that we reduce via NAD and then it transfers its electrons.
- ATP is involved in many different things. Name 3 ATPases that in part produce ATP
- Sodium ATPase, Calcium ATPase, and Myosin ATPase
- These ATPases function where (99% of the time)?
- In the mitochondria
- If you are measuring oxygen consumption, what are you really measuring?
- ATP production
- Where does most ATP production occur, and is oxygen involved?
- Most occurs inside the mitochondria. This occurs aerobically
- Is ATP produced anywhere outside the mitochondria, and if so, is oxygen involved?
- ATP is produced outside the mitochondria, and when this occurs it is done anaerobically
- What are all enzymes?
- Catalysts
- Catalysts are or are not consumed in a reaction?
- They are not consumed in reaction
- What is the major function of catalysts?
- To allow things to occur very rapidly
- Could most reactions that occur with enzymes work without enzymes, and if they could, how would they do this?
- Most could occur, but many would take weeks to months to occur without enzymes
- Are all enzymes proteins?
- The vast majority are, but there is evidence now that ribozymes work catalytically and are not proteins
- How do enzymes work?
- They lower the activation energy, and in doing so this increases the rate of reaction
- So what's the difference between bioenergetics and kinetics?
- Bioenergetics says if the reaction will occur, while kinetics says how fast it will occur
- Do enzymes change the equilibrium constant?
- No
- Will a reaction that is irreversible become reversible if an enzyme is used?
- No
- Do enzymes have high or low specificity?
- Very high specificity
- Specificity refers to what do things?
- The kinds of reactions enzymes catalyze as well as how substrate specific they are
- Do enzymes require anything else to function?
- Oftentimes, they require coenzymes
- What are coenzymes?
- Many are vitamins
- What are 3 examples of coenzymes?
- NAD and FAD are examples, as well ATP, which is thought of as a vitamin
- Is allosteric regulation used in enzymes?
- Yes. For example, hormones use this type of regulation
- What are Ribozymes?
- They are one of the few if not only things that are enzymes but not proteins, and they act as enzymes
- How do they work?
- They are bits of RNA's that have the ability to catalyze a limited number of reactions
- On the surface of the enzyme, what is the region called that the substrate binds to?
- The active site
- What is this new thing called once they've hooked up?
- Enzyme-substrate complex
- Now what happens?
- The ES complex catalyzes the reaction
- What are enzyme inhibitors?
- They are things that bind to the enzyme to prevent it from working
- What is an example of an enzyme inhibitor?
- Many drugs are enzyme inhibitors
- Once the substrate binds, then the _______ occurs.
- catalysis
- After the catalysis occurs, you form what?
- A product, known as an enzyme substrate complex (EP)
- What happens to these two things?
- The product is released and the enzyme is released
- Can the enzyme be used over again?
- Yes, in fact, what often happens in metabolism is you can have one compound converted into another, and then a second, into a third, and fourth, until you get the product you want
- What happens if you heat a molecule kinetically?
- It can allow the molecule to obtain enough energy to reach over the energy barrier. It doesn't lower it though.
- What are the 6 major classes of reactions?
- Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases, and Ligases
- What are oxidoreductases?
- They involve oxidations and reductions, and with these are a transfer of electrons
- How common are oxidoreductases?
- They are very common
- What are transferases?
- They transfer functional groups
- What are hydrolases?
- They catalyze cleavages via water
- Lyases do?
- They are responsible for the addition of a group across a double bond, ie. forms a double bond.
- What are isomerases?
- They allow production of isomers
- What are ligases responsible for?
- They form bonds between things using energy derived from ATP
- What is the surface element called on enzymes that the substrate binds to?
- Active site
- Once its bound, what does it form?
- An enzyme substrate complex
- How does the substrate know to bind there?
- The site has a 3D conformation to allow it to bind
- This site is made up of what?
- Amino acid sidechains
- When a protein folds up, and it brings the amino acid sidechains together, what does it form?
- A pocket or active site
- The kinds of residues found on the active are dependent on what?
- They are dependent on the nature of the substrate
- If we have a positively charged substrate, what we will have somewhere on the active site?
- An electrically charged residue
- Is binding dependent on pH?
- Yes
- What is an alternative to the lock and key theory?
- It is clear that very often when a substrate binds to the enzyme, it may cause a conformation change in the enzyme
- How is it supposed glucose does this?
- Once glucose binds to the active site, parts of the chain (on active site) will move
- How is the idea of conformation change in enzyme function related to mutation?
- Any mutation in a protein, which changes an amino acid, may affect folding, ability of the substrate to bind, and the conformation, and this may lead to a prevention of the correct conformation, so it may look like minor changes in the amino acid may mess up the ability of the acid to function
- Where do cofactors bind if they exist?
- They bind where the enzyme substrate complex is
- When the substrate is bound with cofactors, what does the enzyme do?
- It catalyzes the change in substract to the product
- Where is glucokinase found, and what does it do?
- It is found in the liver and pancreas, and is responsible for converting glucose to glucose-6-phosphate
- Whats the difference between glucokinase interacting with glucose and interacting with galactose
- Glucokinase does not react with galactose because it has an added hydroxyl group at carbon 4 which is oriented towards where galactose would hydrogen bond with glucokinase
- What does trypsin do?
- It hydrolizes peptide bonds in digestion
- What does trypsin work on?
- Lysine or arginine
- What does this show?
- It is highly specific, an dhydrolizes many proteins, and is highly specific for the type of bond in a protein
- What is a model classical curve for a pH curve?
- It shows there is no activity at low or high pH, but in the middle you have maximum activity
- What is the top activity level called?
- pH optima
- What are high ends to this maximum pH range?
- Some go as high as 10, and some are lower
- What is a functional example of why this doesnt work pertaining to carboxyl groups and low pH?
- If an enzyme required charge from a carboxyl group, it wouldn't function at low pH because the carboxyl would be deprotonated