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39 Cards in this Set
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- 3rd side (hint)
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Class 1
Oxidoreductases |
HORD-P
REDOX RX's Hyroxylases Oxidases Reductases Dehyrogenases Peroxidases |
Catalyze redox reactions
. transfer of e- to and from substances. |
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Class 2
Transferases |
KAATT
transfer chemical groups from one molecule to another Kinases Acyltransferases Aminotransferases Transaldolases Transketolases |
Transfer chemical groups from one molecule to another.
2 substrates and 2 products. |
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Class 3
Hydrolases |
P-P-P-DERG
hydrolosis reactions Peptidases Phosphatases phospholipases Deaminases esterases Ribonucleases Glycosidases |
Catalyze hydrolysis reactions.
Transfer -OH from water. |
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Class 4
Lyases |
DASH
molecular bonds formed/broken - NO APT used Decarboxylases Alsolases Synthases Hydratases |
Catalyze reactions where molecular bonds are formed or broken.
do not use ATP. |
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Class 5
Isomerases |
MIRE
Move Double bonds within a molecule Mutases Isomerases Racemases Epimerases |
Involved in the movement of a group or double bond within the same molecule.
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Class 6
Ligases |
CSL
Form C-C bonds & use ATP Carboxylases Synthetases Ligases |
Generally involved in formation of carbon-carbon bonds which necessitate the use of ATP
Contrast these with lyases |
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What do cofactors do?
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causes a conformation change of an active site
they also particpate in temporary bonds between enzymes and substrates. |
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What are cofactors typically made of?
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typically they non-organic molecules.
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What do coenzymes do?
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They transport H+ and small molecules from one enzyme to another.
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What are coenzymes typically made of?
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organic molecules derived from H2O soluble vitamins.
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What is a apoenzyme?
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an enzyme without cofactors or coenzymes.
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What are holoenzymes?
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They are an apoenzyme plus either a metal ion as a cofactor or coenzyme are holoenzymes.
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What are two coenzymes derived from niacin?
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NAD and NADP
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What are two coenzymes from riboflavin?
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FMN and FAD
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What is a prosthetic group?
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Non-protein components conjugated to a protein.
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Give three examples of a prosthetic group.
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Heme in myoglobin and hemoglobin.
Cytochromes Tetrapyrrole ring |
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In enzyme kinetics what is the initial rate proportional too?
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the substrate concentration.
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When must the initial rate be measured?
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before sufficient product has been formed to permit the rverse reaction to occur. This applies only to initial rates.
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in Michaelis-Menten Kinetics what is velocity and what is it dependent on?
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velocity is defined as the rate of formation of product per unit of it.
IE - mm/minute it is dependent on the concentration of substrate. |
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What is the definition of Vmax
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maximal velocity an enzyme can achieve in the presence of infinite substrate.
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what is the defination of Km
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the concentration of substrate at which Vi is equal to half Vmax.
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When is the velocity of a reaction zero order using michaelis logic?
when is it first order? |
It is zero order when the substrate concentrations are very high so that it is constant and independent of substrate concentration.
It is first order when substrate concentration is low (<<Km) it is directly proportional to substrate concentration. |
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How is Km usefull?
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it shows how well a substrate interacts with an enzyme.
Lower Km = more affinty for a a substrate. Smaller number is better 10^-7 better than 10^-6 etc. |
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What is Km measured in?
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Molarity
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how does temperature effect enzymes?
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rate of reaction increases as temp. increases.
it plateaus slightly above body temp. it decreases at the temp increases from this point on. At some point the enzymes will denature if the temperature continues to rise.. no action. |
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How are enzymes related to pH?
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each enzyme exhibits peak activity at narrow pH range (pH optimum)
pH optimum reflects the pH of the body fluid in the the enzyme is normally found. Changes in pH can slowdown/stop a enzymatic reaction. |
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What is competitive inhibition?
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competition for the active site of an enzyme. some substrate can get through but not all because something else is jumping in there too.. plus the "'non" substrate can get stuck because it cannot complete the reaction closing the enzyme permanetely.
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What is uncompetitive inhibition?
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an inhibitor that binds only to the enzyme ubstrate complex and not a free enzyme... messing up the works.
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what is a non0competitive/allosteric inhibition?
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something that binds to the enzyme OUTside of the binding site... mucking up the machine/making it not operate correclty or as effectively. .
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what is irreversible inhibition?
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a covalent interaction in the active site to prevent substrate/enzyme interaction. (this can happen in competitive inhibition)
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on a MM plot what is the effect of a competitive inhibitor on the Vmax/km?
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Vmax stays the same, Km is increased (bad) with competitive inhibitor.
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on a MM plot what is the effect of a noncompetitive inhibitor on the Vmax/km
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km is unchaged
Vmax is decreased (bad) with non-competitive inhibitors. |
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What are some common examples for non-competitive inhibitors?
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lead, organophophates, penicillin, amoxicillin, and the ACE inhibitors, captopril, enalapril, and lisinopril.
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What is an allosteric activator?
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It is a factor that can stimulate enzyme-catalyzed reactions by binding outside the active site. This causes changes in conformation and increases (or can decrease) the ability to bind/lower activation energy.
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What is one way an allosteric regulation process can occur?
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enzyme is plugging along making lots of products until there is too many... then it runs into one of the products.. of the products it is making that binds to it somewhere other than the binding site which changes it shape and slows it down/stops it. Regulating the process.
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What is negative feedback inhibition?
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This can occur when products can "branch" into one of several paths. When one path product starts accumulating it can regulate at the "switch" between paths and turn the reactions in another direction.
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What is the law of mass action?
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principal that reversible reactions will be driven from the side fo the equation where concentration is higher to side where concentration is lower. (think le' chartieliers)
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What else can cause conformation changes in enzymes to regulate production?
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phosphorylation
ADP-ribosylation |
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How can protein-protein interactions regulate enzyme production?
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monomeric G-proteins.
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