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34 Cards in this Set
- Front
- Back
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What do enzymes do?
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enzymes catalyze biological reactions
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Enzymes are what type of macromolecule?
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Enzymes are proteins
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Describe the mechanism of enzyme action.
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enzymes accelerate the rate of chemical reaction w/in a cell.
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How do enzymes accelerate reactions?
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enzymes lower the amount of activation energy.
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Substrate
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(reactant)
what the enzyme works on. |
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Product
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what is produced as a result of reaction.
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enzyme + substrate complex
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enzyme and substrate physically bind to form transition site.
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active site
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(most imp. part)
small cleft or crevice on enzyme, binding site, consists of @ least 3 amino acids |
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What is the difference between absolute and relative specificity?
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Absolute-enzyme will catalyze a particular reaction for one substrate.
(ex.lactase-catalyzes hydrolysis of lactose) relative-less specific,based on the type of bond or linkage. |
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What is an Apoenzyme?
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the protein part of a conjugated enzyme.
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What is a holoenzyme?
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The biochemically active conjugated enzyme produced from an apoenzyme + a cofactor.
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Transferase
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transfer of functional group
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Hydrolase
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hydrolysis reaction,addition of water molec. causes bond to break
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Isomerase
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rearrangement of functional groups converting molec. to isomer
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Ligase
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coupling of 2 compounds using ATP
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Oxydireductase
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catalyzes oxidation-reduction reactions, adds oxygen to hydrogen atoms removed from substrate
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Lyase
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removal of functional group for form double bond
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Alcohol Dehydrogenase
CH3CH2OH+NAD+--CH3CHO+NADH+H+ |
dimer,oxydireductase
consists of 2 polypeptides,metalloenzyme(zinc) humans have 6 dif.ones 2 cofactors NAD+, NADH ethylene glycol is comp inhib |
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Factors that influence enzyme activity
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Temperature
PH substrate concentration enzyme concentration concentration of end product |
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What is optimum temp. and optimum PH?
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The temp. or ph @ which an enzyme exhibits maximum activity.
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What is an enzyme inhibitor?
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substance that slows or stops the normal catalytic function of an enzyme by binding to it.
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Types of Inhibition
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Irreversible
Competetive reversible Non-competetive reversible |
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Irreversible
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binds via covalent bond to enzyme,perm. inactivates it by changing tertiary or quarternary structure. (ex.insectides,nerve gas,cyanide,penecillin)
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Competetive reversible
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sufficeintly resembles an enzyme substrate in shape and charge,binds to active site (ex.sulfa drugs)
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Non-competetive reversible
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binds away from active site,which changes the shape (ex.heavy metal ions,lead/arsenic/mercury)
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What is genetic control of enzyme activity?
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enzymes are produced only when necessary, absence of substrate or presence of product controls protein synthesis. (ex.Lac Operon, if lactose is present,enzymes are produced)
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What is an allosteric enzyme?
What does it do? |
Often the 1st in a series of reactions.It is regulated by a modulator. inhibits or activates.allows cell to respond to cell activity/environment. binds away from active site. (ex.enzyme sensitive to concentration of product)similar to non-comp.inhibitor
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What is a zymogen?
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enzymes produced in an inactive or proenzyme form
(ex.pepsinogen,trypsinogen, prothrombin,fibrinogen) |
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What is the difference between the lock n key theory and induced fit theory
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lock n key - substrate and enzyme have complementary shapes
induced fit - enzyme undergoes change in 3D shape to fit better w/substrate |
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What is the difference between simple and conjugated enzymes?
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simple-composed only of amino acids (protein)
conjugated-composed of protein and nonprotein part |
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What is a cofactor
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a cofactor is the nonprotein part of a conjugated enzyme
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What are some examples of enzymes w/different metal ions?
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alcohol dehydrogenase-zinc
carboxy pepsidase-zinc catylase-iron phosphatase-magnesium |
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Where are metal ions found in the diet? Where are coenzymes found in the diet?
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metal ions - minerals
coenzymes - vitamins (ex.NAD+, FAD+ derived from vitamin B) |
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What do coenzymes do in a reaction?
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accept or donate-electrons,specific atom,or functional groups
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