myoglobin and HB Flashcards
1
Q
requirements for a storage molecule
A
high affinity for O2 - 1mol per mol Mb
higher affinity then carrier
2
Q
requirements for carrier
5 points
A
high capacity for O2 - 1 mol Hb for 4 O2 high specificity high affinity when O2 conc is high low affinity when O2 conc is low other functions such as removal of metabolite
3
Q
myoglobin contains
A
haem group - Fe2+ protoporphyrin ix ring
8 alpha helices (globin polypeptide)
4
Q
protoporphyrin ix ring structure
A
Fe2+ co-ordinated by 4 N atoms
His 93 binds at 5th position using N
O2 binds at 6th at an angle
5
Q
why does O2 bind at an angle
A
because of distal His which stabilises O2 and helps prevent release of super oxide radical O2-
stops O2 taking e- from fe2+ and
Fe3+ cant bind O2 so thats why it is released and forms metmyoglobin
6
Q
in the absences of O2 what happens
A
water binds
7
Q
what happens to the structure when water does bind
A
d
