Thursday, September 9, 2010

Hemoglobin

Structure of haemoglobin

Human produces different kinds of haemoglobin during life; embryonic, fetal and adult. The structure of haemoglobin during different stage of life is different. Adult has two types of haemoglobin; major α2β2 and minor α2δ2. HbF (α2γ2) can be found during gestation. Basically, each globin enfolds a single heme moiety that consists of protoporphyrin IV ring and iron in ferrous state (Fe2+). A molecule of haemoglobin consists of four heme moiety that is capable of transporting up to four molecules of oxygen. It is hydrophilic exteriorly and hydrophobic interiorly. The pairing mechanism is important in this process because the excess or lack of one subtype of globins chain can lead to formation of insoluble precipitates that can cause damage to the red blood cells. The quaternary structure is maintained by bonds formed between globins chains such as α1β1 and α1β2.

Function of haemoglobin.

The function of haemoglobin is for the oxygen transportation to the cells. The affinity of haemoglobin reduces at lower pH and lower oxygen tension. At alveolus in which the partial pressure of oxygen is higher, oxygen tends to bind, at first slowly to haemoglobin then rapidly. This condition occurs due to the abrupt increase in haemoglobin affinity towards oxygen when some oxygen are readily bound to that molecules. At lower pH, oxygen is readily dissociates due to the Bohr effects. This is due to higher affinity of proton to deoxyhemoglobin. Other molecule that is important for oxygen affinity is 2,3-biphosphoglycerate. Haemoglobin in adult has higher affinity towards this substances compared to fetal haemoglobin. It is important to lower the oxygen affinity towards haemoglobin.

Itadakimasu!

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(Excuse me. Menu please)

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(Here you are)

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(Topping?)

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(Just a moment. I like pepperoni. How about Fairuz?)

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(I like mushrooms)

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(How about onion?)

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(I hate onion a lot)

Fareez: Sumimasen. Rāji piza onegaishimasu. Peparoni to masshurūmu.
(Excuse me. A large pizza, please. Pepperoni and mushrooms)

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(Water please)

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