Myoglobin/Hemoglobin 2

muscle cells/ stores oxygen to make it available during muscle activity

myoglobin found primarily where? why?

in red blood cells to transport oxygen from lungs to tisse\ues

hemoglobin found where? why?

Allosteric proteins

proteins that can change conformation

Changes the behaviour of other binding sites.

In the new conformation, the protein’s ability to react to a second molecule is altered

IN allosteric, what happens when one site binds

A conformational change that increases oxygen affinity for remaining subunits.

what happens in hemoglobin when oxygen binds to one subunit.

a ligand and a positive allosteric effector

In hemoglobin, oxygen is both a what and what?

The Bohr effect

Describes how increased Co2 and H+ in tissues cause hemoglobin to release oxygen more readily

The chemical environment around it provides a signal

How does hemoglobin know when to hold onto O2 and when to let it go?

CO2

Active tissues produce what?

More H+, so decrease pH

More CO2 in tissues leads to more what?

decrease affinity for O2, oxygen is released. A RIGHT SHIFT

Increased CO2 and H+ have what effect on hemoglobins affinity for oxygen?

Stabilizes the low-affinity T-state so that O2 is released.

H+ stabilizes what state of hemoglobin?

Affinity for O2 decreases, causing it to release.

When the concentration of CO2 and H+ is high, what happens when species bind to hemoglobin?

Promotes binding of oxygen and release of CO2

High concentration of oxygen in the lungs causes what to happen for binding of oxygen

bicarbonate buffer

THIS system allows CO2 produced in tissues and transported safely to the lungs

bicarbonate buffer in the tissues:

bicarbonate (HCO3-)

Most Co2 is transported in the blood as what?

the Bohr affect

H+ produced in bicarbonate buffer contributes to what?

bicarbonate buffer in the lungs

Carbon monoxide

colorless, odorless gas that is present in the atmosphere at low levels but can build up

250x greater affinity that oxygen

Carbon monoxide hemoglobin affinity:

COHb

As CO exposure increases, more hemoglobin becomes:

increased breathing during exercise

what can cause faster CO uptake

2-3 biphosphoglycerate (BPG)

molecule that interacts with hemoglobin and modulates its O2 affinity. produced in red blood cells as a side product of glycolysis

decreases the affinity of hemoglobin for O2 so it is an allosteric inhibitor

BPG binds hemoglobin at a distant site from oxygen site and :

positively charged amino acids that interact with negatively charged groups on BPG

The cavity of BPG is lined with what?

increased BPG stabilizes the T-state of Hb, decreases oxygen affinity, and more O2 is released

how does increased BPG lead to release of oxygen to tissues?

Has a lower affinity for BPG and higher affinity for O2

How does fetal hemoglobin have higher affinity for O2

it is compoed of y subunits as opposed to beta subunits

what gives fetal hemoglobin lower affinity for BPG

a hydrophobic patch on the surface of the beta subunit that causes hemoglobin tetramers to polymerize into long fibrils

the glutamate to valine mutation in beta hemoglobin subunit (sickle cell) creates what?

long fibrils distort the shape. The distorted cells don’t fit through the capillaries. Can interup oxygen delivery to tissues

what distorts rbc in sickle cell

Where malaria is historically common. ONe copy of the allele provides some protection against severe malaria

Where is sickle cell most comon