I6 Flashcards
How does protein crystallograohy work?
X-rays hit a protein crystal and hits a detector giving a diffraction pattern which is analysed on a computer.
What is resolution and what is never seen on electron density plots?
Electron density contour plots show conc of electrons throughout a molecule
H+ is never seen as there are no electrons present
Explain Abundant, labile and thermodynamically stable
Abundant- Can be achieved by expending energy using coupled processes
Labile- Rapid assembly of metal cores and rapid association/dissassociation of substrates
TS- Stable Metal-ligand binds- allow proteins to evolve to bind one type of metal
What is the most abundant TM in biology?
Iron 1mg lost per day- Iron storage + transport (transferrin) very efficient!
Iron+Oxygen=free radicals + toxic products
Where is iron stored?
Ferretin- Stores 4,500nFe3+ ions
When empty- apoferretin
What protein transports copper?
Ceruoplasmin
Made in liver carries 6 Cu ions
What are some factors that affect reduction potential for metal centres?
Sigma/pi donors favour high OS and lower reduction potential
Pi-acceptor ligands require low OS and produce high reduction potentials
Changes in metal spin state
Steric factors can favour one OS/spin state - tuning reduction potential by second coordination sphere restricting structural changes
What is Mössbauer Spectroscopy?
Only for iron, must be recoilless nuclear resonance adsorption of gamma-radiation. Also has to be solid in ’solid state’ (frozen liquid)
Emitted photon is adsorbed by 57^Fe
Ea-Es= Shift
Transition energy depends on charge density at nucleus
