Bioinorganic Chem

Question 1

what is bioinorganic Chem?

Answer 1

using coordination chem to understand biological pathways

biology uses metal ions and ligands to form complexes

Question 2

metals can be

Answer 2

major or trace

Question 3

amino acids and proteins

Answer 3

aa side chains with N, O and S (have lone pairs) can be ligands

Question 4

prosthetic groups

Answer 4

some proteins have these groups that are essential for non-amino acid complexes

• porphyrin group (Haem moiety) is found in haemoglobin and has a -2 charge. it is a tetra dentate ligand
• Corrine macrocyclic ligand has a -1 charge and is a tetradentate ligand

Question 5

metalloprotein

Answer 5

if prosthetic groups contain a metal ion within the protein. Fe and Co are common

Question 6

oxygen carriers

Answer 6

myoglobin and haemoglobin (made of 4 Mb)
haem prosthetic groups have active sites where O2 binds
Hb transports O2 in blood and Mb in muscles
haem connects to protein via histamine aa using N to coordinate to Fe centre which leaves a vacant spot for O2

Question 7

equation of Mb

Answer 7

deoxy-Mb + O2 —-> ox-Mb

deoxy-Mb is square pyramidal, Fe2+, high spin
oxy-Mb is octahedral, Fe3+ and low spin

Question 8

effects of CO

Answer 8

CO binds to haem 200x more strongly than O2

equilibrium can be reversed by breathing concentrated oxygen

Question 9

haemocyanin - a copper metalloprotein

Answer 9

like haemoglobin except with copper and for molluscs and anthropods
blue when oxygenated
two copper centres, 1+ oxidation, coordinated to three histamine ligands via N atoms

Question 10

haemocyanin equation

Answer 10

deoxyhaemocyanin —> oxyhaemocyanin

deoxy is Cu+ and the Cu atoms are far apart
oxy is Cu2+ and the O2 bridges for Cu centres

Question 11

Zinc based enzymes

Answer 11

200 enzymes
likes to bind to O and N donors
prefers coordination number 4 (can be 5 or 6) and has a tetrahedral geometry
does not change ox state and is redox stable
acid-base catalyst
usually coordinated to histamine or cysteine

Question 12

carbonic anhydrase (Zn enzyme)

Answer 12

enzyme for reversible hydration of CO2 to form bicarbonate ion and a proton
used in photosynthesis and pH control
Sn centre coordinated to three His-N ligands and one H2O (tetrahedral)

Question 13

platinum in medicine

Answer 13

cisplatin is an anti cancer agent
square planar, cis arrangement
in the body, Cl- are exchanged for H2O making a charged/active species that can bind to DNA and prevent transcription
it reacts with guanine and H2O is replaced with G

satraplantin is a pro-drug (activated where needed)
Pt4+ becomes Pt2+ - square planar

Question 14

radioactive transition metals

Answer 14

radiation makes them easy to follow

have large formation constants so they don’t react

Question 15

chromium 51Cr

Answer 15

isotope that emits radiation

injected into blood stream and shows how well the renal system is working (flow rate through kidneys)

Question 16

64Cu

Answer 16

isotope that emits radiation
uses Cu2+ macrocyclic complex - octahedral
large Kf

Question 17

Rubredoxin FeS metalloprotein

Answer 17

protein
reduction of O22- in anaerobic bacteria and e- carriers (Fe can be oxidised and reduced)
reduced by NADH
has two Cys-x-y-Cys sequences allowing chelation
sequences are separated by 20-30 residuals allowing flexibility for four S atoms to coordinate
tetrahedral redox-active iron site
4 or 5 unpaired electrons (Fe3+ has high spin)