Chapter 7 Chem 132

Front 1

4 factors effecting Enzyme rate

Back 1

1. [Enzyme]: high rate with high [ ]

2.[Substrate]: high [s]=high V

3. T: ~50C (>50 denatures protein)

4. pH: specific to enzyme

Front 2

Formula for Enzyme Velocity

from Substrate to product

Back 2

V= -- Change in [S]/ change in t

=Change in [P]/ change in t

Front 3

Shape of Velocity vs. Substrate

Back 3

Hyperbolic curve indicates:

- high enzyme act. in low [s]

- Enzyme saturation with high [S]

-Informs speed of E

Front 4

What does Michaelis Menten Eqt show

Back 4

It's the rate equation for enzyme catalyzed description of Hyperbolic curve

Front 5

Km in curve Indicates

Back 5

How efficient an E selects its substrate and coverts it to product. It's the [S] when E is 1/2 saturated.

Front 6

Vmax on graph indicates

Back 6

Max reaction velocity when there's high [S] and E becomes saturated

Front 7

To determine Km

Back 7

Vmax must be known

= [S] at 1/2 Vmax

Front 8

Catalytic Rate (K cat) constant determines

Back 8

how quickly an enzyme can act.

Front 9

Eqt for Kcat

Back 9

Vmax/ [E] total

Front 10

Meaning of high Kcat

Back 10

Enzyme converts substrate to product right away

Front 11

What determines catalytic efficiency

Back 11

The value of K cat/ Km represents enzyme's overall ability to convert substrate to product than values alone.

Front 12

What does the Lineweaver Burk Plot do

Back 12

Linearizes Michaelis-Menten Kinetics data.

Takes the reciprocal

Front 13

Lineweaver Burk Equation

Back 13

1 = (Km) 1 + 1

___ __________ ___

V (Vmax) [s] Vmax

Y= m X + b

Front 14

Types of enzymes that don't fit the Michaelis Menten Model

Back 14

1) Multiple substrate Reaction ( O-R , tranfarase rxn)

2)Multistep reactions

3) Nonhyperbolic reaction ( In oligomeric enzymes with multiple act. site)

Front 15

Irreversible Inhibition

Back 15

Any reagent that COVALENTLY modifies an AA side chain

*Suicide substrate: enter enzyme act. site and begin to react just as normal substrate would

Front 16

Competitive inhibitor

Back 16

Bind to the active site of the enzyme resembles substrate in size and chemical properties so it binds to enzyme but lacks electronic structure that allows it to react

*high [s] reverses inhibitor

Front 17

Effects of Competitive inhibitors on Km and Vmas

Back 17

-Increase K: inhibitor prevents substrate from reaching act. site and decreases affinity .

-Doesnt effect Vmax: Inhibitor binds reversible, allows E to occasionally enter act. site.

Front 18

Transition state analogs

Back 18

Compound mimics transition state and can take advantage of features in act. site in the ways the substrate can't.

*Better inhibitors than substrate analogs

Front 19

Noncompetitive inhibitors

Back 19

Binds to sire on the enzyme OTHER THAN act. site. Creates a conformational change that affects structure or chemical properties of act. site

Front 20

Effects of Vmax, Kcat and Km with NONCOMPETITIVE inhibitors

Back 20

Kcat and Vmax: Kcat is affected so Vmax is lowered to the same degree

-Km lowered to the same degree

Front 21

Uncompetitive inhibitors

Back 21

Bind to ES complex in multisubstrate Rxn. Prevents reaction from continuing and yielding product

Front 22

Effect of Uncompetitive inhibitors on Vmax and Km

Back 22

Vmax is decreased

Km is unchanged

Front 23

Allosteric regulation

Back 23

can inhibit or enhance enzyme activity in oligomeric enzymes (multiple Act. site)

Front 24

Allosteric feedback inhibition

Back 24

When high [I] = shuts down its own synthesis by blocking earlier step

Front 25

the Negative effector

Back 25

A substance that diminishes an enzyme's act through allosteric inhibition