Fallis

Question 1

Hard acids prefer what?

Answer 1

Hard bases

Question 2

Soft acids prefer what?

Answer 2

Soft bases

Question 3

8 examples of hard acids

Answer 3

+H+, Li+, Na+, K+, Mg2+, Ca2+, Cr3+ and Co3+

Question 4

5 examples of hard bases

Answer 4

RNH2, NH3, O donors (H2O, OH-, RO-), F- and Cl-

Question 5

6 examples of soft acids

Answer 5

Cu(I), Ag(I), Au(I), Hg(I), Hg(II) and Ti(I)

Question 6

Rank the soft bases from softest to least

Answer 6

I- > Br- > CO > CN-

Question 7

4 examples of borderline acids

Answer 7

Fe2+, Co2+, Cs+, Pb2+

Question 8

7 examples of borderline bases

Answer 8

RCO2-, imidazole, N2, N3-, Br-, NO3- and SO42-

Question 9

How are high reaction rates achieved by the entatic effect?

Answer 9

mimicking the transition state of the catalysed reaction, or the enzyme binds the TS more strongly than starting materials and products

Question 10

What oxidation states are cycled by Rubredoxin?

Answer 10

Fe2+ and Fe3+

Question 11

How does rubredoxin cycle between both oxidation states of Fe?

Answer 11

2+ longer bond length, so an intermediate bond length is used and metal is distorted towards the TS

Question 12

Cu (I) prefers what kind of donors? Give an example

Answer 12

Soft donors - eg S

Question 13

Cu (II) prefers what kind of donors? Give 2 examples

Answer 13

Hard donors - eg N & O

Question 14

what’s the relationship between oxidation state and bond lengths generally?

Answer 14

Increasing ox state leads to ionic radius contracting and shorter bond lengths

Question 15

What does the coordinated water molecule on a Zn enzyme act as?

Answer 15

A resting state, which can be replaced by a substrate

Question 16

What catalyst would be needed for CO2 and why?

Answer 16

CO2 is both a LA and LB so requires a bifunctional LA/LB catalyst

Question 17

What re the uses of synthetic modelling?

Answer 17

To make models that look like a natural system and that have the natural system’s function

Question 18

what to SODs catalyse

Answer 18

the dismutation of superoxide radicals into molecular oxygen and hydrogen peroxide

Question 19

Describe the bovine erythrocyte SOD

Answer 19

Dinuclear Cu and Zn centres, bridging His residue with His residues, 1 Asp, 1 Arg and 1 Thr

Question 20

How can small anions (F- and N3-) affect Cu,Zn dinuclear/boving erythrocyte SODs?

Answer 20

Can compete with superoxide to act as inhibitors, binding to the active site

Question 21

Mn3+ SOD suggests what mechanism?

Answer 21

inner sphere

Question 22

Mn2+ SOD suggests what mechanism?

Answer 22

outer sphere

Question 23

If 2 reactions differ by ~0.4V or more, will the reaction go to completion?

Answer 23

yes

Question 24

where does Cytc transfer electrons to?

Answer 24

from cytochrome c reductase to cytochrome c oxidase

Question 25

Questions about mutations of enzymes

Answer 25

does charge at active site change? if it does, affects electrostatics and E
HSAB arguments

Question 26

What to look out for if a reaction is reversible or irreversible?

Answer 26

If E=0.4V or higher it’s irreversible!

Question 27

Why does pKa of water lower as oxidation state increases?

Answer 27

as ox state increases, metal pulls ED of the water molecules towards itself, tendency of water to release protons increases

Question 28

examples of PCET

Answer 28

dismutation of superoxide and oxidation of water to molecular oxygen in photosynthesis

Question 29

Role of tyrz in PSII

Answer 29

tyrz is oxidised by the energy of P680+, resetting the ability of P680 to absorb another photon and release another photo-dissociated electron

Question 30

pH = …. (ratios!)

Answer 30

pH = pKa + log [A-]/[HA]