protein function

Question 1

proteins needs to have reversible transient __ ___

Answer 1

chemical equilibrium

Question 2

a molecule that can bind to a protein is called

Answer 2

ligand

Question 3

ligand binds where

Answer 3

binding site on protein (non covalent forces to allow interactions (weak))

Question 4

protein binding with ligand at binding site need to have what three properites

Answer 4

specific, reversible, transient

Question 5

ligand can bind to a protein and changes _____ of it; ligand is released

Answer 5

conformation

Question 6

multiple subnits = ____ structure

Answer 6

quartenary

Question 7

equation for binding of proteins dissociation (need to memorize)

Answer 7

Kd = [P][L] / [PL]

Question 8

Ka = 1/ Kd they are

Answer 8

inversely proportional

Question 9

theta = [PL] / ____

Answer 9

[P]tot
(theta is half of dissociation)

Question 10

ligand concentration is more useful for measurement because

Answer 10

kept in low amount, solid and not changing when bonded

Question 11

the smaller the Kd the ____ the affinity = ____ binding

Answer 11

higher, tighter

Question 12

ligand and Kd are given in ___ units, theta in percentage

Answer 12

M

Question 13

protein side chains lack affinity for ___

Answer 13

o2

Question 14

heme Fe2+ are suitable to caption O2, what is the protein that allows oxygen storage

Answer 14

myoglobin

Question 15

circulating/ transporting oxygen-binding protein (high kd, doesn’t bind oxygen)

Answer 15

hemoglobin

Question 15

main oxygen storage protein (high affinity for oxygen, low affinity (can bind more and remaining bound))

Answer 15

myoglobin

Question 16

hemoglobin can switch ____ to have high affinity or lower affinity to O2 to keep it or give it up

Answer 16

structure

Question 17

heme is rigid and planar; it has four nitrogens which provide coordination sites for ___ ____ (two sites available for binding)

Answer 17

heme iron

Question 18

the myoglobin (3°) two free binding (valences) will associate with histidine (on F helix) and the other ____

Answer 18

oxygen (only bind 1 oxygen)

Question 19

CO has similiar size and shape to O2 and binds 20,000 times better than O2 why?

Answer 19

CO has a filled lone electron pair that can be donated to vacant D orbitals (much tighter interaction)

Question 20

erythrocytes carry __

Answer 20

hemoglobin

Question 21

hemoglobin is a tetramer and each beta and alpha subunit will bind ___; how many will it bind?

Answer 21

oxygen; 4

Question 22

two states of hemoglobin

Answer 22

oxyhemoglobin, deoxyhemoglobin

Question 23

in the tissues what state is hemoglobin in

Answer 23

deoxyhemoglobin (giving it out)

Question 24

the binding curve of oxygen to hemoglobin is signmoidal because it can switch between what

Answer 24

high affinity and low affinity

Question 25

hemoglobin two states

Answer 25

r and t

Question 26

in the t state, hemoglobin has ___ affinity for O2, preferred state in deoxyhemoglobin

Answer 26

low

Question 27

Tense state characterized by iron ___ of plane and thermodynamically stable (iron is out of plane because His-HC3 is protonated; cannot interact)

Answer 27

out

Question 28

the _ state is thermodynamically less stable and has high affinity for O2 (iron sits in the middle of the structure)

Answer 28

R

Question 29

based on hill plot you can tell high vs low affinity; nH > 1 is positive cooperativity which means

Answer 29

oxygen will bind and allow the next subsequent oxygen to bind

Question 30

on hill plot myoglobin would have nH = 1, why?

Answer 30

there is no cooperatively in oxygen binding because it only binds one oxygen

Question 31

nH < 1 =

Answer 31

negative cooperativity (not altering conformation to allow binding of next oxygen (ex. co2))

Question 33

is His HC3 is protonated the iron is pulled out of plane and is tense state, lowering pH can cause this which is known as

Answer 33

bohr effect

Question 34

low pH cause a ___ shift, hemoglobin is in tense state (protonated)

Answer 34

right

Question 35

when CO2 binds to amino terminus on hemoglobin, it released a proton which does what

Answer 35

furthers bohr effect and stabilizes t state

Question 36

salt bridges (-BPG) are formed in the middle of hemoglobin in what state

Answer 36

Tense

Question 37

higher altitude, high BPG causes what state

Answer 37

tense, deoxyhemoglobin