Globular Proteins Flashcards
Structure of protein which is the result of H-bonding producing regular repeated structure
Secondary structure
What are the two heme proteins?
Hemoglobin and myoglobin
How many Oxygen binds to hemoglobin
4
What is the structure of heme?
Complex of protoporphyrin IX and ferrous iron (Fe2+)
Heme is also called __________ because iron is held by 4 nitrogen of porphyrin ring
Tetrapyrrole
What links the 4 molecules of pyrrole?
A-methylyne bridges
The organic component protoporphyrin is made up of?
- 4 pyrrole rings
- 4 methyl groups
- 2 vinyl groups
- 2 propionate
The central iron is normally of _______ form or oxidized state
Ferrous
Monomeric heme found in muscle tissue where it serves as an intracellular storage site of oxygen
Myoglobin
Myoglobin secondary structure contains how many percent of A- helices?
75%
Myoglobin is comprised of how many separate right handed A-helices?
8
R-groups in the surface of the molecule are generally ___________, making the molecule relatively water soluble
Hydrophilic
Structure of proteins composed of sequence of amino acids
Primary structure
The oxygen binding site contains heme prosthetic grp with Fe in the center and __________ residues located above and below
Histidine
Oxidation of iron int what state renders the molecule incapable of normal oxygen binding
Ferric Fe3+
The proximal histidine is also termed?
His F8 or His 93
The iron forms additional bond with the proximal histidine on the ___________.
5th coordinating position
What stabilizes the oxygen bound to the iron atom on the 6th coordinating position?
Distal histidine residue or His E7 or His 64
Heme part of hemoglobin is synthesized in the _______ and ________ of immature cells, while _______ protein are synthesized by ribosones in cytosol.
Mitochondria and cytosol
Globin
What composes hemoglobin?
2 Alpha and 2 Beta polypeptide chain
The capacity of hemoglobin to bind oxygen depends on the presence of __________.
Heme
In hemoglobin, the 5th coordination site is occupied by ___________ of histidine residue
Imidazole ring
A state of hemoglobinwhere the 6 th coordination site is unoccupied.
Deoxyhemoglobin
In hemoglobin, the iron lies approximately ______ outside the porphyrin plane because iron is slightly too large to fit into the well defined hole
0.4 A
