allosteric affects

Question 1

non allosteric affects

Answer 1

occur directly at the active site of an enzyme (when the substrate binds)

Question 2

allosteric affects

Answer 2

Occurs at a site other than the active site. A product binds to the allosteric site leading to a conformational change of the active site.
non competitive inhibition

Question 3

allosteric activation

Answer 3

Site becomes available to substrates when a molecule binds to allosteric site

Question 4

allosteric deactivation

Answer 4

the active site becomes unavailable to the substrates when a molecule binds to the allosteric site

Question 5

allosterism

Answer 5

the responsivness of allosteric proteins relies on the ability to relay events at one ligand binding site to a distinct site

Question 6

feedback inhibition

Answer 6

when a downstream product inhibits an upstream enzyme (A product down the chain binds to an enzyme that produces a product earlier in the chain leading to less formation of the downstream products) - prevents accumalation of products

Question 7

feed forward activation

Answer 7

an upstream product activates a downstream enzyme- increases metabolic flow and increases rate of reactions

Question 8

relay capactiy

Answer 8

this is the conformational changes that occur at the active site due to allosteric events at another site

Question 9

how can the relay capacity exist

Answer 9

1. weak interactions in proteins
2. oligomeric nature of allosteric proteins - made up of multiple subunits

Question 10

allosteric theory

Answer 10

predicts that allosteric proteins exist in alternate conformations.
Inactive (T) and active (R) states which exist in rapid equilibrium
Binding of substrates and allosteric activators stabilize the R state and shift the equilbirum to R
Allosteric inhibitors stabilize T and shift the equilibirum to T

Question 11

Km

Answer 11

substrate concentration at which the rate of reaction is 50% of the Vmax

Question 12

How do allosteric proteins affect Km

Answer 12

activators lower Km (shift curve to the left) inhibitors raise Km (shift curve to the right)

Question 13

allosteric enzyme regulation

Answer 13

1. Enzyme changes conformation on binding
2. Results in change in enzyme performance
3. alters Km of the enzyme for the substrate

Question 14

Types of hemglobin

Answer 14

HbA(97%) HbA2(2-3%) and HbF (< 1%)

Question 15

equations for hemoglobin

Answer 15

HbO2 (in tissues) —> O2 + Hb
Hb —> H+ and CO2 transported to lungs

Question 16

homotropic ligand

Answer 16

chemically identical to substrate

Question 17

heterotropic ligand

Answer 17

chemically different to substrate

Question 18

homotropic effector (ligand) example

Answer 18

O2 has a positive affect on O2 binding

Question 19

heterotropic effector

Answer 19

H+, CO2 - negative affect on O2 binding
O2 - negative affect on H+, CO2, and z binding

Question 20

Mb

Answer 20

Myoglobin - oxygen binding cell facilitates diffusion of oxygen to tissues and muscles

Question 21

allosteric properties of Hb

Answer 21

1. Cooperative binding of oxygen
2. the Bohr effect
3. Effect of Carbon dioxide
4. Effect of 2,3 bisphosphoglycerate
5. Effect of temperature
6. allosteric inhibition by H+ ions
7. Chloride shift

Question 22

Cooperative binding of oxygen

Answer 22

When one O2 molecule binds it makes it easier for more O2 molecules to bind

Question 23

The Bohr effect

Answer 23

In acidic conditions hemoglobin affinity for oxygen decreases happens in active tissues so hemoglobin releases oxygen more easily

Question 24

Effects of carbon dioxide

Answer 24

CO2 can bind directly to the globin chain which reduces the hemoglobin affinity for oxygen so it releases oxygen easily in areas with high CO2

Question 25

Effects of 2,3 Bisphosphate

Answer 25

Made by RBC during glycolisis it binds to deoxygenated hemoglobin reducing the oxygen for affinity . Helps release oxygen into tissues during low O2 conditions (like high altitude)

Question 26

Effect of temperature

Answer 26

High temperatures reduce hemoglobins affinity for oxygen

Question 27

Allosteric inhibition by H+ ions

Answer 27

Protons bind hemoglobin leads to a conformational change that favors the T state leading to low O2 affinity.

Question 28

chloride shift

Answer 28

Cl- ions stabilize deoxygenated form of hemoglobin to promote O2 release

Question 29

Contrasting oxygen binding curves of Mb and Hb

Answer 29

The Mb curve is hyperbolic - single equilibrium constant Mb is non allosteric Mb has a higher affinity for O2 than Hb at a low pO2 The Hb O2 binding curve is sigmodial - positive cooperativity in the binding of one O2 per heme group

Question 30

BPG

Answer 30

In red cells negativley charged BPG binds to deoxyHb reducing Hbs O2 affinity by crosslinking deoxyHb in addition to the 8 salt links of the T state. BPG ensures that O2 flows from mother - fetus as HbF has a higher O2 affinity than maternal HbA. Because HbF's y chains bind BPG less strongly than HbA beta chains bind BPG