General Physiology

Hemoglobin VS Myoglobin


Hemoglobin and myoglobin are the two oxygen-binding proteins present in large multicellular organisms.

Hemoglobin transports oxygen in the blood and is located in the erythrocytes; while Myoglobin stores the oxygen in the muscles.

~ Distribution ~

HB : In Blood

MB : In muscles

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~ structure ~

HB : 4 polypeptide chains ( 4 units ) = 2 alpha + 2 beta

MB : single polypeptide chain ( 1 unit ) = similar to the beta unit of hemoglobin

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~ Oxygen capacity ~

HB : four Oxygen molecules (4 O2  )

MB : One Oxygen molecule ( 1 O2  )

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~ Affinity for Oxygen ~

HB : low affinity to Oxygen , and it increases gradually with the increase in O2 concentration

MB : High affinity to oxygen  even in very low O2 concentration

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.:: Hint ::.

Fetal hemoglobin consists also of 4 units = 2 alpha and 2 Gamma ” Not Beta ”

fetal Hemoglobin ” HBF ” Has higher affinity for O2  than Adults hemoglobin “HBA

which promotes the transfer of O2 from the maternal circulation ( Mother ) to the fetal circulation ( baby ) .

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references :

” BIOS instant notes in biochemisrty “

” Biochemisrty text book by Garrett & Grisham

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