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Enzymes
Enzymes
67
Biochemistry
Undergraduate 3
03/10/2014

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Term
What reactions do oxidoreductases catalyze?
Definition
redox reactions
Term
What are the two types of oxidoreductases?
Definition
reductase, oxidase
Term
What is another name for oxidase?
Definition
dehydrogenase
Term
What is the role of transferases?
Definition
transferring a group from one molecule to another
Term
What reactions do transaminases catalyze?
Definition
transfer of an amino group
Term
What reaction do kinases catalyze?
Definition
transfer of a phosphate group
Term
What reactions do hydrolases catalyze?
Definition
cleave bonds by adding water
Term
What are the examples of hydrolases?
Definition
phosphatases, peptidases, lipases
Term
What reactions do lyases catalyze?
Definition
removal of groups to form double bonds or break double bonds
Term
What are the two types of lyases?
Definition
decarboyxlases, synthases
Term
What reactions do isomerases catalyze?
Definition
intramolecular rearrangements
Term
What reactions do isomerases catalyze?
Definition
intramolecular rearrangements
Term
What are the two types of isomerses?
Definition
epimerases, mutases
Term
In most cases enzyme names end in...
Definition
-ase
Term
What does HRP stand for?
Definition
horse radish peroxidase
Term
What are the four historically named enzymes?
Definition
catalase, pepsin, chymotrypsin, trypsin
Term
How does an enzyme speed a reaction?
Definition
lowering the activation energy
Term
Rates of uncatalyzed reactions ______ as the substrate concentration ______
Definition
increases, increases
Term
What is the first stage of rate of enzyme-catalyzed reactions?
Definition
formation of an enzyme-substrate complex
Term
What is the second stage of rate of enzyme-catalyzed reactions?
Definition
slow conversion to product
Term
What is the rate of enzyme-catalyzed reactions limited by?
Definition
enzyme availalbility
Term
What is step 0 of the enzyme-substrate complex?
Definition
presence of an enzyme and a substrate
Term
What is the result of step 1 of the enzyme-substrate complex?
Definition
Formation of the enzyme-substrate complex
Term
What is the result of step 2 in the enzyme-substrate complex?
Definition
Enzyme-Substrate complex in a transition state
Term
What is teh result of step 3 of the enzyme-substrate complex?
Definition
The formation of the Enzyme-product complex
Term
What is the result of step 4 of the enzyme-substrate complex?
Definition
Separation of the enzyme-product complex into 2 pieces.
Term
What is the part of the enzyme that combine with the substrate called?
Definition
active site
Term
What are teh R groups at active site called?
Definition
catalytic groups
Term
The shape of the active site is _______ to the shape of the substrate
Definition
complimentary
Term
How does the enzyme attract and hold the substrate?
Definition
weak noncovalent interactions
Term
What determines the specificity of the active site?
Definition
Conformation of the active site
Term
In the lock and key model the enzyme is the....
Definition
lock
Term
In the lock and key model the substrate is considered the....
Definition
key
Term
What is a weakness of the lock and key enzyme model?
Definition
failure to take into account proteins conformational changes to accomadate a substrate molecule
Term
What is the major assumption of the induced fit enzyme model?
Definition
the enzyme active site conforms to accommodate the substrate molecule
Term
What is enzyme specificity?
Definition
the ability of an enzyme to bind only one, or a very few, substrates thereby catalyzing only a single reaction
Term
What are two common hydrolases?
Definition
urease, lactase
Term
How many classes of enzyme specificty are there?
Definition
4
Term
What is absolute enzyme specificity?
Definition
enzyme reacts with only one substrate
Term
What enzyme class catalyzes reaction involves molecules with the same functional group?
Definition
Group
Term
What enzyme class catalyzed the formation or breakage of only certain category/type of bond?
Definition
linkage
Term
What class of enzymes recognize only one of two enantiomers?
Definition
stereochemical
Term
How does the enzyme promote a faster chemical reaction?
Definition
The substrate's interacts with the enzyme, forming a new less energetically stable shape
Term
The transition state has features of both _____ and _____
Definition
substrate, enzyme
Term
How many possible types of transition state changes are there?
Definition
3
Term
WHat is the first possible type of transition state change?
Definition
the enzyme might put "stress" on a bond facilitating bond breakage
Term
What is the second type of transition state change?
Definition
the enzyme might bring two reactants into close proximity and maintain proper orientation
Term
What is the third type of transition state change?
Definition
enzyme might modify the pH of the microenvironment, donating or accepting a H+
Term
What is a holoenzyme?
Definition
combination of an enzyme and a co-enzyme
Term
What is the polypeptide portion of an enzyme called?
Definition
apoenzyme
Term
What is the nonprotein prosthetic group of an enzyme called?
Definition
cofactor
Term
What is the role of cofactors?
Definition
bind to the enzyme to maintain the correct configuration of the active site
Term
What substances can cofactors be?
Definition
organometallic, metal ions, organic compounds
Term
How is a conezyme bound to the enzyme?
Definition
weak interactions/hydrogen bonds
Term
Most coenzymes carry _____ or ______ groups
Definition
electrons, small
Term
Many coenzymes have modified _______ in their structure
Definition
vitamins
Term
What is a hydride?
Definition
H plus 2 electrons
Term
What part of the NAD+ accepts the hydride?
Definition
nicotinamide
Term
Where does the hydride come from for the NAD+ reaction?
Definition
alcohol to be oxidized
Term
Where does the alcohol lose a proton (H+) to?
Definition
the solvent
Term
NAD+ becomes what?
Definition
NADH
Term
NADP becomes what?
Definition
NADPH
Term
FAD becomes what?
Definition
FADH2
Term
Where is the enzyme pepsin located?
Definition
stomach
Term
Where is chymotrypsin located?
Definition
small intestine
Term
The rate of an uncatalyzed reaction will ______ proportionally with temperature ______
Definition
increase, increase
Term
What is the usually the optimal temperature for enzymes?
Definition
37 C
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