Introduction to Bioinorganic Chemistry

Question 1

What happens to atomic radius down the group + across the period?

Answer 1

Increases

Question 2

What happens to ionisation energy down groups 1 + 2 and across period 1?

Answer 2

Increases

Question 3

What is the equation for ionisation energy?

Answer 3

A(g) —-> A+(g) + e-(g)

Question 4

What is the equation for e- affinity?

Answer 4

A+(g) + e-(g) —-> A-(g)

Question 5

Where are elements that have highest e- affinity?

Answer 5

Top right

Question 6

What is electronegativity?

Answer 6

Ability of an atom within a compound to attract e- towards itself

Question 7

Where are atoms that are the most electronegative?

Answer 7

Top right

Question 8

What are hardest atoms?

Answer 8

Highest ionisation energies
= small atoms, near fluorine

Question 9

What are softest atoms?

Answer 9

Low ionisation energy

Question 10

What are hard acid and bases?

Answer 10

Less polarisable
Form bonds with more ionic character

Question 11

What are catalytic metals?

Answer 11

Many enzymes have metals attached to active site to act as catalyst

Question 12

What factors influence the role of metal?

Answer 12

Valency
Ionic radius
Polarizability
Hydration energy
Radius of hydrated ion

Question 13

What do hard acids prefer?
Works vice versa with soft acids

Answer 13

Hard bases

Question 14

What is linear?

Answer 14

sp

Question 15

What is equilateral triangle?

Answer 15

sp2

Question 16

What is tetrahedron?

Answer 16

sp3

Question 17

What is triagonal bi-pyramidal?

Answer 17

sp3d

Question 18

What is octahedron?

Answer 18

sp3d2

Question 19

What do different metals prefer?

Answer 19

Different coordination numbers

Question 20

What are the most common coordination numbers found in biological systems?

Answer 20

4 = square planar tetrahedral
6 = octahedral

Question 21

What can a ligand be?

Answer 21

Monodentate OR polydentate

Question 22

What is monodentate?

Answer 22

Only one point of attachment to metal

Question 23

What is polydentate?

Answer 23

More than one point of attachment too metal

Question 24

What is ciprofloxacin?

Answer 24

Hard Lewis acid

Question 25

What is a macrocyclic molecule?

Answer 25

Cyclic molecule (at least 9 atoms), containing 3 donor atoms - typically N, O, S or P

Question 26

What are macrocyclic complexes?

Answer 26

More thermodynamically + kinetically stable than non-cyclic ligands

Question 27

Are polydentate ligands more stable than monodentate?

Answer 27

YES

Question 28

What is the increasing stability of mono, poly + macrocyclic known as?

Answer 28

Chelate effect

Question 29

What is clinical significance of chelation?

Answer 29

Chelation changes physical + chemical characteristics of both components

Question 30

What are tetracyclines?

Answer 30

Broad-spectrum antibiotics Treat the clap

Question 31

Describe tetracyclines mode of action

Answer 31

Bacteriostatic agents Target 30s subunit Block binding of aminoacyl tRNA in A-site

Question 32

Which metal is involved in mode of action of tetracyclines?

Answer 32

Mg2+

Question 33

What do tetracyclines form?

Answer 33

Chelates with Ca2+, Mg2+, Al3+, Fe2+ + Zn2+

Question 34

What chelates do tetracyclines form with M3+?

Answer 34

3:1 drug-metal chelates

Question 35

What chelates do tetracyclines form with M2+?

Answer 35

2:1 drug-metal chelates

Question 36

What do Al or Mg hydroxide-based antacids do?

Answer 36

Reduce absorption of tetracyclines

Question 37

What are tetracyclines not recommended for? Ca2+ chelates

Answer 37

Kids under 12 = teeth yellow Pregnant women = effect on skeletal growth

Question 38

What can metal ions do and what does this mean?

Answer 38

Stabilise conjugate bases = pKa value of parent acid lowered

Question 39

What does it mean if an acid has a lower pKa?

Answer 39

STRONGER

Question 40

What does it mean if a base has a higher pKa?

Answer 40

STRONGER

Question 41

pKa = pH

Answer 41

50% ionised

Question 42

What do all carbonic anhydrase inhibitors contain?

Answer 42

All share sulphonamide = WAs

Question 43

What is carbonic anhydrase involved in?

Answer 43

Regulation of acid/base balance Production of bicarbonate rich aq humor secretion

Question 44

What does carbonic anhydrase do?

Answer 44

Catalyse reaction between H2O + CO2 to for carbonic acid

Question 45

What is the equation for reaction between H2O + CO2?

Answer 45

CO2 (g) + H2O ⇌ carbonic acid ⇌ hydrogencarbonate (bicarbonate) + H+

Question 46

Which metal does carbonic anhydrase contain?

Answer 46

Zn2+

Question 47

Why is Zn2+ (metals) so important?

Answer 47

Metal drives it = remove Zn2+ = process doesn't work = catalyses process by modulating pKa of H2O = form OH- + giving correct geometry for cleft

Question 48

Where does Zn2+ sit in carbonic anhydrase?

Answer 48

Bottom cleft, which has 2 faces

Question 49

What is the hydrophobic face important for? Carbonic anhydrase

Answer 49

Binding the substrate

Question 50

What is the hydrophilic face important for? Carbonic anhydrase

Answer 50

Shuttling proton

Question 51

Does Ca2+ have a gradient?

Answer 51

YES = through different cellular compartments

Question 52

What is the coordination number for Mg2+?

Answer 52

6

Question 53

What is the coordination number for Ca2+?

Answer 53

7

Question 54

What can Mg2+ + Ca2+ both be thought of as?

Answer 54

Lewis acids

Question 55

What is Mg2+ main role?

Answer 55

Catalytic sites of DNA polymerase

Question 56

What do protein kinases do?

Answer 56

Add phosphate group

Question 57

What do phosphatases do?

Answer 57

Remove phosphate group

Question 58

What is the phosphate supplied as?

Answer 58

Mg-ATP DOESN'T work without Mg2+

Question 59

How is RNA different to DNA?

Answer 59

Perform catalytic functions

Question 60

What does tRNA contain?

Answer 60

Half-crucifixes Mg2+ hold this shape

Question 61

What do ribosomes require?

Answer 61

Mg2+ ions to catalyse their splicing reactions

Question 62

Why is Mg2+ important in muscle cells?

Answer 62

Carries ATP/ADP so has to be present for it to be delivered

Question 63

What does Ca2+ regularly do?

Answer 63

Exchange H2O with other ligands

Question 64

What is calmodulin?

Answer 64

Protein involved in mediation of Ca2+ signal

Question 65

Describe structure of calmodulin

Answer 65

Small, acidic protein Dumbbell shape Binds 4x Ca2+

Question 66

What are the major donor groups for Ca2+?

Answer 66

Carbonyl + carboxylate groups