Quat Struc homo-multimers Flashcards
What are homo multimers?
Copies of the same polypeptide chain associated non-covalently
Homo multimers are usually what
symmetrical
Homo multimers allows for what cooperativity?
Allosteric that results in increased activity
An example of a homo multimer
semaphorins
what are hetero multimers?
two or more different polypeptide chains
An example of a hetero multimer
Hemoglobin
What chains make the heterodimer for hemoglobin
alpha and beta and theres 2 copies of these
What were the first proteins that 3D structures were determined for
Myoglobin and Hemoglobin
Why does Oxygen need to bind to heme?
Oxygen is poorly soluble in aqueous solutions. It can bind to Iron but that is too reactive and so its incoporated into heme - hemoglobin
What does heme consist of?
a complex organic ring structure to which a single iron is bound
How many coordination bonds does Iron atom in heme have
6
Describe the coordination bonds to the iron atom in heme
4 bonded to nitrogen part of the flat ring and 2 perpendicular to the ring
The coordination nitrogen atom helps prevent what from happening in heme
Prevents the iron atom from being converted to Fe3+ state (ferric)
Iron in what state binds to oxygen reversibly
fe2+
One of the remaining coordinaion sites is occupied by what in heme
His residue
