The main function of hemoglobin

Normal people know that the human body needs to take in protein every day to maintain the body's needs, but in fact there are many different types of protein, among which hemoglobin is a protein that has a transport function in the human body. The human body's hemoglobin is mainly present in the blood, so hemoglobin plays a vital role in blood transportation. Next, we will explain in detail the human body functions related to hemoglobin.

Functions of human hemoglobin

Hemoglobin is a protein (abbreviated as Hb or HGB) responsible for carrying oxygen in higher organisms. It is the protein that makes blood red. Hemoglobin consists of four chains, two α chains and two β chains, each of which has a ring-shaped heme containing an iron atom. Oxygen is bound to iron atoms and transported in the blood. The characteristics of hemoglobin are: it easily combines with oxygen in places with high oxygen content; and it easily separates from oxygen in places with low oxygen content. This characteristic of hemoglobin enables red blood cells to transport oxygen.

1. Function

Hemoglobin is used in biochemical research, culture of influenza virus, gonococci, tularemia bacillus, streptococci, pneumococci, etc., and pigments.

2. Normal reference value

Adult male: 130-175 g/L

Adult female: 115-150 g/L

Newborn: 170-200 g/L

Adolescents (children): 110-160 g/L

3. Working Principle

The process of hemoglobin combining with oxygen is a very magical process. First, an oxygen molecule binds to one of the four subunits of hemoglobin. After binding with oxygen, the structure of globin changes, causing the entire structure of hemoglobin to change. This change makes it easier for the second oxygen molecule to find another subunit of hemoglobin to bind to than the first oxygen molecule, and its binding will further promote the binding of the third oxygen molecule, and so on until the four subunits that make up hemoglobin bind to four oxygen molecules respectively. The same is true for the release of oxygen within tissues. The departure of one oxygen molecule stimulates the departure of another until all oxygen molecules are completely released. This interesting phenomenon is called synergistic effect.

1. Synergy

Due to the synergistic effect of the heme molecular structure, the binding curve of hemoglobin and oxygen is S-shaped. Within a specific range, as the oxygen content in the environment changes, the binding rate of hemoglobin and oxygen molecules undergoes a drastic change process. The oxygen concentration in the tissues of the organism and the oxygen concentration in the lung tissue happen to be on both sides of this mutation. Therefore, in the lung tissue, hemoglobin can fully bind to oxygen, and in other parts of the body it can fully release the oxygen molecules it carries. However, when the oxygen content in the environment is very high or very low, the oxygen binding curve of hemoglobin is very flat, and huge fluctuations in oxygen concentration will hardly cause significant changes in the binding rate of hemoglobin and oxygen. Therefore, even if healthy people breathe pure oxygen, the blood's ability to carry oxygen will not be significantly improved. From this perspective, for healthy people, the psychological implications of oxygen inhalation are far greater than its physiological effects.

In addition to carrying oxygen, hemoglobin can also bind to carbon dioxide, carbon monoxide, and cyanide ions in the same way as oxygen. The only difference is the strength of the binding. Once carbon monoxide and cyanide ions bind to hemoglobin, it is difficult for them to leave. This is the principle of gas poisoning. In this case, other substances with stronger binding ability with these substances can be used to detoxify. For example, carbon monoxide poisoning can be treated with intravenous injection of methylene blue.

2. Conjugation of proteins

A conjugated protein consisting of heme and globin, which is the colored component of vertebrate blood. Its main function is to transport oxygen, and it also plays a role in maintaining the acid-base balance of blood. Heme is a porphyrin compound containing divalent iron. Iron has six coordination bonds, four of which are connected to the ring structure of hemoglobin and are in the same plane. One of the other two coordination bonds is connected to the protein part, and the other is connected to oxygen. Globin contains four subunits (α2β2), each of which is attached to a heme prosthetic group. The amino acid sequences of the α chain (containing 141 amino acid residues) and β chain (containing 146 amino acid residues) of human and many animal hemoglobin have been determined, and their quaternary structures have also been determined by X-ray diffraction structural analysis. Point mutations in the hemoglobin gene result in the production of abnormal hemoglobin. Hundreds of abnormal hemoglobins have been discovered, but only a small fraction cause disease, the most common and best understood of which is sickle cell anemia.