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70 Cards in this Set
- Front
- Back
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What does Km measure?
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how strongly the substrate is bound
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What is an Inhibitor?
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a substance that interferes with the action of the E and slows the rate of product formation (V decreases)
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Example of Reversible Inhibitor
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Ibuprofen
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What is a reversible inhibitor?
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binds to enzyme slowing V; can subsequently be released leaving enzyme in its original state (V increases)
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Example of Irreversible Inhibitor
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Aspirin
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What is an irreversible inhibitor?
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reacts or binds to enzyme producing and enzyme that is inactive and cannot be reactivated
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What are three classes of Reversible Inhibitors?
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1) Competitive
2) Non-competitive 3) Uncompetitive |
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What is a competitive inhibitor?
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binds at the same site as S; competes with S for the enzyme's binding site
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What is a non competitive inhibitor?
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binds at some other site on the enzyme (not where S binds) but causes changes such that S can not be converted to product as efficiently; binds to both E and ES (affects ability to form product)
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What is an uncompetitive inhibitor?
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ONLY binds to ES
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Effects on Km and Vmax of a Competitive Inhibitor
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Km increases, Vmax stays the same
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Effects on Km and Vmax of an Uncompetitive Inhibitor
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Km decreases, Vmax decreases, ration of Vmax:Km stays the same
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Effects on Km and Vmax of a Non Competitive Inhibitor
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Km stays the same, Vmax decreases
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Examples of an irreversible inhibitor
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DIPF, TPCK
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CTP is a/an _____________ inhibitor
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feedback
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ATC is made of 12 polypeptides. What is the break down?
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6 Catalytic -> carbamoyl phosphate & aspartate
6 Regulatory -> where ATP & CTP bind |
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What is Proteolysis?
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breaking of peptide bonds with water
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What is a zymogen?
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inactive form of an enzymes that becomes active after peptide bonds are broken
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When an inactive enzyme is changed to an active enzyme, changes occur in the ___________ structure
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tertiary
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What happens in the induced fit model
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The enzyme changes shape around substrate; substrate does NOT change shape
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Rate Acceleration
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Rate with Enzyme/Rate without Enzyme = 10^10
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What accounts for 10^2 of the reaction rate of enzymes?
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-participation of catalytic group
-acid/base catalyst -nucleophiles |
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What accounts for 10^4, 10^5 of the reaction rate of enzymes?
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-proximity effect
-transition state stabilization |
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Proximity Effect
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substances participating in catalysis are correct orientation (because of active site) to produce product effectively
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Transition State stabilization
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Enzyme binds to transition state (S*) more tightly than S
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Amino acid that can act alternately between acid and base; pKa is near neutral pH (~6)
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Histidine
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Function of chymotrypsin mechanism
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hydrolysis of peptide bonds on the carboxy side of aromatics
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Amino acids in catalytic triad
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Asp, His, Ser
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Site Directed Mutogenesis
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use genetic means to replace a certain amino acid with some other amino acid
Asp -> Glu |
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Relation between trypsin, chymotrypsin, elastase
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sequence & structural homology, common ancestral serine protease by divergent evolution
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Subtilisin
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hydrolyzes peptide bonds using a catalytic triad and molecular mechanism
-has no homology to chymotrypsin, trypsin and elastase |
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What are cofactors? List two types
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non amino acid substance that participate in enzymatic reactions
1) metal ions 2) organic cofactors = coenzymes |
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Chymotrypsin, Trypsin, Elastase have similar sequence and structural homology, and have a common ancestor. Example of what type of evolution?
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divergent
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Subtilisin
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hydrolyzes peptide bonds using a catalytic triad and molecular mechanism; no homology to chymotrypsin, trypsin, or elastase
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Most prevalent quinone
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ubiquinone
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Epimer
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stereoisomers that differ in configuration around a single chiral center
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Diastereomers
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non-enantiomeric stereoisomers
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Aldehyde + Alcohol -> ?
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hemiacetal
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Alcohol + hemiacetal -> ?
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full acetal /glycoside
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Sucrose is made up of which two monosaccharides?
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alpha-D-glucose, beta-D-fructose
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Lactose is made up of which two monosaccharides?
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beta-D-galactose, beta-D-glucose
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Which vitamin is formed in the skin and regulates intestinal absorption of calcium and deposition in the bones?
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Vitamin D
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A 20 carbon lipid molecule indirectly from beta carotene
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Vitamin A
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A deficiency in this vitamin may lead to fragile red blood cells and neurological damage
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Vitamin E
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Coenzymes that participate in oxidation/reduction reactions
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NAD+, NADP+, FAD, FMN, Ubiquinone
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Coenzyme that acts as acyl transfer carriers
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Coenzyme A
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Name the fat soluble vitamins
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Vitamins A, D, E, K
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Structural difference between chitin and cellulose
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Chitin is a polymer of N-acetyl-beta-D-glucosamine with beta(1,4) linkage
Cellulose is a polymer of beta-D-glucose with beta (1,4) linkage |
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Difference in function of glycogen and starch
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Starch: energy storage molecule in plants
Glycogen: short term energy storage in animals |
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Similarity in structure between glycogen and starch
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alpha(1,4) linkage of alpha-glucose
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Difference in structure between amylose and amylopectin
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Amylopectin has alpha(1,6) branching; Amylose is not branched
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Which carbon is oxidized in aldoses?
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C1
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Which carbon is oxidized in ketoses?
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C2
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What is an anomeric carbon?
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Most oxidized carbon; the C attached to two oxygen atoms in a ring; chiral!!
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Glycosidic bond
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primary structural linkage in all polymers of monosaccharides
acetal linkage when the anomeric carbon is condensed with an alcohol, amine, or thiol |
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IUPAC name for maltose
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alpha-D-glucopyranosyl (1,4) alpha-D-glucopyranose
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IUPAC name for cellobiose
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beta-D-glucopyranosyl (1,4) beta-D-glucopyranose
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IUPAC name for sucrose
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alpha-D-glucopyranosyl (1,2)-beta-D - fructofuranoside
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IUPAC name for lactose
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beta-D-galactopyranosyl (1,4) D-glucose
(glucose can be alpha or beta) |
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What is a reducing sugar?
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ability to reduce metal ions (Cu2+ or Ag+) to insoluble products
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Name some reducing sugars
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glucose, maltose, lactose, cellobiose
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What is a non-reducing sugar?
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carbohydrates that are not readily oxidized because both anomeric carbon atoms are fixed in a glycosidic linkage
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Name a non-reducing sugar
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sucrose
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Major role of NAD+ and NADP+
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oxidation-reduction reactions involving two electron transfer
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Major role of FMN and FAD
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oxidation-reduction reactions involving one and two electron transfers
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Major role of ATP
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transfer of phosphoryl or nucleotidyl groups
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Major role of ubiquinone (coenzyme Q)
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lipid-soluble electron carrier
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Which coenzyme contains a thiol group that acts as a "reactive center"?
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Coenzyme A
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What are FAD and FMN derived from?
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Riboflavin
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Riboflavin consists of a 5 carbon alcohol ribitol linked to the N-10 atom of a heterocyclic ring called
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isoalloxazine
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