Enzyme Kinetics and Inhibition Flashcards

Question

Order sequential

Answer 1

Specific order for substrate binding and product leaving "A has to go in first"

Answer 2

Random order for substrate binding and product leaving "Either A or B can go into the reaction first"

Answer 3

One substrate binds and release product before second substrate binds and release product A goes in P comes out * enzyme intermediate* B goes in and Q comes out

Answer 4

Bind the enzyme with noncovalent interactions Dissociate rapidly Allow the enzyme to recover its original activity

Answer 5

Bind the enzyme with covalent interactions targeting a critical residue for catalysis Permanent inactivation of the enzyme

Answer 6

Binds to only the free enzyme Compete with substrate for active site Usually resembles shape and structure of substrate (or transition state) --> lacks functionality for reaction Hinders reaction by interfering with substrate binding and reducing amount of ES complex

Answer 7

reduced rate is same as noncompetitive inhibitor at very low [S] Degree of inhibition decreases with increasing [S] --> low substrate concentration is the best place for the inhibitor to work Km decreases Vm stays the same Kcat/Km decreases

Answer 8

Have key structural features that mimic the substrate

Answer 9

Stable compounds that resemble the transition state in structure and polarity or charge

Answer 10

Binds only to ES Complex (substrate must be bound to enzyme) at a site different from active site but created by substrate-enzyme interaction Lacks structural resemblance to substrate

Answer 11

Hinders reaction by distorting active site and making catalytically inactive ^^catalytic residues cannot line up properly Km decreases by the same factor of Vm Vm decreases by the same factor of Km Catalytically efficiency stays the same (same slope)

Answer 12

Rate constants don't change, we're looking at them when the inhibitors are present --> called apparent changes

Answer 13

Doesn't do much as low [S] (rate is same as control) but inhibition increases with increasing [S]

Answer 14

Binds with same Ki to free enzyme or ES complex at site different from active site Lacks structural resemblance to substrate

Answer 15

Hinders reaction by distorting enzyme structure and preventing alignment of catalytic center

Answer 16

Vm --> decrease Km --> no change Catalytic efficiency --> decrease *increasing [S] cannot overcome effects*

Answer 17

Degrees of inhibition is constant with increasing [S]

Answer 18

(1-voi/vo) X 100

Answer 19

1/(1+ [I]/Ki)

Answer 20

1/(1+[I]/Ki)

Answer 21

1/(1+[I]/Ki)

Answer 22

1/(1+[I]/Ki)

Answer 23

Result in permanent inactivation by forming stable covalent bonds with functional groups involved in enzyme activity

Answer 24

[E]t decreases Vm decreases but no change in Km ^this is because inhibitors remove free enzymes from the reaction Operate within the active site

Answer 25

Group specific reagents covalently interact with specific side chains of enzyme residues

Answer 26

Structurally similar to substrate and covalently bind with active-site residues More specific than group specific reagents

Answer 27

Also called mechanism-based inhibitors or suicide in activators Bind at the active site and "trick" the enzyme into activating the catalytic mechanism A chemically reactive intermediate is produced which covalently modifies the enzyme and results in permanent inactivation ^^permanent inactivation of the enzyme is a result of the enzyme's own participation

Answer 28

Does not obey Michaelis-Menten Kinetics Shows a sigmoidal dependence of reaction velocity on substrate concentration

Answer 29

These enzymes are typically rate-determining enzymes in metabolic pathways or at a junction where the substrate can be used for more than one pathway

Answer 30

Involves noncovalent binding of a ligand (effector) to a site other than the active site (Regulatory or allosteric site) --> this binding affects the activity of the active site Allosteric enzymes are generally oligomers (>1 subunit) such that interaction on one subunit affects the others (+ or - cooperativity)

Answer 31

Effector is same as substrate Site is usually adjacent to active site (adjoining subunit) Interaction almost always increases activity (sigmoidal curve)

Answer 32

Effector is different from substrate Site is "true" allosteric site Interaction increases or decreases activity

Answer 33

Allosteric control actually changes the rate constants instead of the apparent change

Answer 34

Effector-induced conformational changes in the enzyme can alter activity by changing Km (k class) and Vm (v class) or both

Answer 35

Binds to activator site and increases activity --> decreases Km

Answer 36

Binds to inhibitory site and decreases activity --> increases Km

Answer 37

Thru feedback inhibition

Answer 38

Proteins that either have Stimulatory or inhibitory reversible interactions with enzymes

Answer 39

Regulatory protein that stimulates activity Senses intracellular Ca2+ concentration and activates proteins when calcium levels rise

Answer 40

Regulatory protein that stimulates activity Enhances activity of a serine protease to accelerate the blood clotting cascade

Answer 41

Regulatory protein that inhibits activity Inhibitors PKA catalytic subunits until binding of cAMP causes dissociation of regulatory and catalytic subunits

Answer 42

Catalytic properties of enzymes are modified by adding/removing charged groups (phosphate, sulfate, acetate) --> that causes conformational change and alter their function most common: the phosphorylation/dephosphorylation cycle of specific serine, threonine, and tyrosine residues Rate depends on the concentration of kinases (phosphate example)

Answer 43

Many enzymes are synthesized as an inactive precursor called a pro enzyme or zymogen

Enzyme Kinetics and Inhibition Flashcards

(70 cards)