Lecture 8: Hemeglobin

Question 0

differences and similarities of Myoglobin and hemeglobin?

Answer 0

both made of alpha helicies and have at least 1 heme group that contains Fe,
Myoglobin - no quaternary structure, 1 polypeptide chain, binds 1 O
Hemeglobin is 4 subunits, 4 polypeptide chains 4 O

Question 1

Myoglobin can undergo cooperatively binding of Oxygen like hemeglobin? true/false

Answer 1

False, only 1 binding site for myglobin

Question 2

The Heme bound iron can be either the ferrous Fe2 or the Ferric Fe3, but which is necessary for O binding?

Answer 2

ferrous. Fe2

Question 3

When Oxygen binds to the Iron in the Heme group, Does the Fe move into or out of the ring/plane?

Answer 3

It pops in when O is binding. Think attracted to eachother like magnets.

Question 4

How many Heme structures in Hemeglobin? how many Iron atoms in Hemeglobin?

Answer 4

4 and 4

Question 5

Hemeglobin’s vital structure is that contains 4 subunits which is why its referred to as a ______mer ?

Answer 5

TETRAmer

Question 6

The 4 subunits of Hemeglobin are what type of polypeptide Chains? and how many different chains are in the 4 subunits?

Answer 6

Globin chains… Globular
4 polypeptides, each subunit is 1 polypeptide chain. This is why hemeglobin has a quaternary structure and Myoglobin does not

Question 7

Why does the formation of RBCS require the Jetison of organelles like Mitochondria?

Answer 7

B/c the mitochondria would compete for Oxygen.

Question 8

The Heme group in Hemeglobin, consists of 2 components, organic component and a central atom, what are these 2 ?

Answer 8

1. organic component is — protoporphyrin
2. iron atom is central atom
   this is the piece of cheese He was talking about, ie planar.

Question 9

The globins of Heme and Myoglobin are made of which secondary structures? and how many of each?

Answer 9

A- helices only

and 8 of them

Question 10

What is the prize winning A.A. and its R group in hemeglobin that does the work of holding the Cheese in place? Whats the cheese called again?

Answer 10

its Histidine and its imidazole ring that Chelates or Holds the Iron.
Iron being the central atom of the Cheese, or
Heme group, which is comprised of the Fe atom and porphyrin ring

Question 11

How many coordination points are in hemes (not hemeglobins) oxygenated and deoxygenated state?

Answer 11

Oxygenated- more with O - 6 coordinate points

deoxygenated - 5, 4 pts of porphyrin ring and 1 pt for Fe.

Question 12

There are ___# of His groups in the globin chain of each of the 4 globin subunits. Where are they located in the chain? 8 helices, a-h.

Answer 12

2 His groups
E7 eth helix and 7th residue
F8 fth helix and 8th residue

Question 13

Fun fact that could be tested upon, in reading. What happens to Fe ion when Oxygen binds to heme… other than it moving into the plane… How can it move into the plane?

Answer 13

With Oxygen, the electrons around Ferrous ion rearrange, which results in the ion becoming effectively smaller and able to move into the ring.

Question 14

What are the 3 Nutritional Needs for heme development and to prevent anemia?

Answer 14

Folic acid, B12 and B6

Question 15

The proximal His on the Globin Chain is at ____ & Stabilizes/chelates the _____, & distal His on the same Globin chain is at ____ & stabilizes the _____?

Answer 15

Proximal is at F8 and stabilizes the Fe ion as coordination pt 5.
Distal, at E7 stabilizes O in a way that allow for 2 things
1. Oxygen can more readily leave the heme complex
2. Oxygen will be less likely to leave as a superoxide anion, which is disasterous for 2 reasons, its a radical and it would leave Ferric Fe3 which can’t bind future O.

Question 16

Fe can be Essential or Toxic, explain this and the 2 forms?

Answer 16

Ferrous Ion Fe2, is necessary to bind oxygen.
Ferric Ion Fe3, which Fe does slightly become when it shares its electron with bound oxygen, which helps it get smaller and move into the ring and is really why Oxygen is bound, its this covalent bond. And yes Its big trouble if O radical leave and steals the Fe e-, this is the reason for the distal His. to stabilize this O exchange and prevent the super oxide O2- from leaving before fully giving back the e- to Fe.

Question 17

The distal Histadine stablizes The Oxygen through what kind of bond? and whats the component/ring of the R group that offers this bonding?

Answer 17

Hydrogen bond

Imidazol group’s Nitrogen, of His

Question 18

It’s the Imidazol group on Proximally and distally that bind what? and with what type of bond?

Answer 18

Proximally, covalent bond to Fe from N in imidazol.

Distally, hydrogen bond to O, from H off imidazol

Question 19

What colors the blood red and is responsible for binding O.

Answer 19

Fe