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Definition
| Substance which increases the speed of a reaction without undergoing any change |
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Term
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Definition
| Protein (or RNA) that acts as a catalyst in living beings |
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| Four aspects enzymes differ from ordinary chemical catalysts |
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Definition
(1) higher reaction rates
(2) mild reaction conditions
(3) great specificty
capacity for regulation |
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Term
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Definition
Internationally accepted method
(1) oxidoreductase- oxid-red reactions
(2) transfereases- transfer c-, N-, P-containing groups
(3)hydrolases-cleaving of bongs with water
(4) lyases- cleavage of c-c, c-s, or c-n bonds
(5) isomerases
(6) ligases- form bonds between carbon and o, s, n |
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Term
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Definition
Small molecule required for catalytic activity of an enzyme
Metal ions, organic molecules |
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Term
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Definition
| Cofactor transiently associated to enzyme |
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Definition
Cofactor that is an organic molecule
Ex. vitamins |
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Definition
| Cofactors that are permanently associated with their protein via covalent or noncovalent interactions (heme) |
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Definition
| Catalytically active enzyme-cofactor |
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Definition
| Enzymatically inactive protein resulting from removal of cofactor |
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Definition
| Small molecule that binds to larger one |
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Definition
| Molecule undergoing the reaction (bound by active site of enzyme) |
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Definition
Region of enzyme that binds substrate and where catalytic reaction occurs
AA are not contiguous in protein |
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Definition
Conversion of substrate to form product by making or breaking bonds
S + E-->EP<-->E+P
[image] |
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Term
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Definition
Model for enzyme-substrate binding
Active site has shape complementary to substrate
Does not explain catalysis event
[image] |
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Term
| How are enzymes specific for their substrates? |
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Definition
(1) functional group specificity
(2) stereospecificity |
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Term
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Definition
Model of enzyme-substrate binding
Active site distorts both enzyme and substrate
Active site becomes complementary to substrate only after substrate is bound
[image] |
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Definition
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Definition
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Definition
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Term
| Lactate dehydrogenase binds... |
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Definition
L-lactate
(not D-lactate) |
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Term
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Definition
| Thermodynamic term referring to energy available to do work (G) |
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Term
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Definition
Normal energetically favorable state of molecule
Lower free energy = more stable molecule |
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Term
| Equilibrium of a reaction |
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Definition
Reflects difference in free energy between ground states of product and substrate
ΔG=Gp-Gs |
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Term
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Definition
Substrates must form a higher energy transition state before they can be converted into products
Transition state is a short-lived intermediate in which old chemical bonds are being broken and new ones are formed |
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Term
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Definition
Difference between free energy of transition state and that of the substrate
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Term
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Definition
| Created by formation of multiple weak noncovalent interactions between enzyme and substrate which are optimized in the transition state |
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Term
| Penicillin's action as an antibiotic |
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Definition
Transition state analog that binds to glyopeptidyl transferase (GT) which is required by bacteria to synthesize cell walls
GT catalyzes ala-ala cross-linking reaction
Penicillin covalently attaches to serine residue in active site of GT--inactive |
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Term
| Mechanisms of enzyme catalysis |
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Definition
(1) Catalysis by proximity
(2) Covalent catalysis
(3) Catalysis by strain
(4) General acid-base catalysis |
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