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Flashcards in Allosteric Enzymes Deck (18):
1

Allosteric enzymes usually display ___ cooperatively with their substrate

positive

2

In regards to allosteric enzymes, the binding of one substrate molecule facilitates....

the binding of subsequent molecules to the enzyme

3

Allosteric enzyme has more than one ___ ___ site

substrate binding

4

v = Vm[S]^n / K0.5 + [S]^n

What is this equation's name?

the hill equation

5

The Hill number (n) is a measure of the degree of ___

cooperativity

6

The larger the value of n, the greater the cooperativity, and the greater the ____ of the curve

sigmoidocity

7

If n = 1, describe the cooperativity

there is none

8

Explain the difference between K0.5 and Km since both represent [S] at 1/2 Vmax

since the rate constants for an allosteric enzyme are different than those for a michaelis-menten enzyme, the two constants are not equal

9

Enzymes with positive cooperative kinetics have a more ___ range of activity response to [S] and act more like a "___"

narrow; switch

10

Allosteric enzymes may be in a "tense" or "relaxed" conformation. At low [S], the enzyme is in the ____ conformation. Binding of [S} promotes a conformation change to the ____ conformation

tense; relaxed

note: tense is inactive, relaxed is active

11

The binding of S to an allosteric enzyme, which increases the affinity of the other catalytic sites for S is an example of ____ regulation

Homotropic

12

True or false? Homotropic regulation is almost always negative

false; postive

13

Hetertropic regulation - describe

a regulatory molecule distinct from the substrate which binds to a site other than the catalytic site and modulates the activity of the enzyme

14

Heterotropic effectors interact with a site other than the active site. They can have a ___ or a ___ effect.

postive or negative

15

In regards to heterotropic effectors, what do V-system effectors do?

the effectors may affect the catalytic rate, and thus influence the Vmax - can be positive or negative

16

In regards to heterotropic effectors, what do K-system effectors do?

effectors affect the binding of substrate and thus influence the K0.5 - can be positive or negative

17

Describe what V-system effectors look like on a plot

Positive or negative lines star off with uninhibited line and then as the slope increases, the V-system effectors go higher or lower but maintain the same sigmoidal curve

18

Describe what K-system effectors look like on a plot

Positive or negative lines start at 0 with uninhibited line but then immediately go vertical (positive) or more horizontal (negative) and do not retain sigmoidal shape