The main difference between alpha and beta chains in hemoglobin is that alpha-chain hemoglobin contains 141 amino acids, whereas beta-chain hemoglobin contains 146 amino acids.
Alpha and beta chains in hemoglobin are the two chain types that occur in hemoglobin. They are polypeptide chains.
Key Areas Covered
1. What is Hemoglobin
– Definition, Anatomy, Importance
2. What is the Alpha Chain in Hemoglobin
– Definition, Features, Importance
3. What is the Beta Chain in Hemoglobin
– Definition, Features, Importance
4. Similarities Between Alpha and Beta Chain in Hemoglobin
– Outline of Common Features
5. Difference Between Alpha and Beta Chain in Hemoglobin
– Comparison of Key Differences
5. FAQ – Alpha and Beta Chain in Hemoglobin
– Answers to frequently asked questions
Key Terms
Alpha Chain in Hemoglobin, Beta Chain in Hemoglobin
What is Hemoglobin
Hemoglobin is an iron-containing metalloprotein that occurs in the red blood cells of vertebrates. Therefore, it is the main form of oxygen-transporting protein of vertebrates, carrying oxygen from the lungs or gills to the metabolizing tissues of the body. Generally, 96% of the dry weight of the red blood cells of mammals accounts for hemoglobin. Moreover, the binding of hemoglobin into oxygen forms oxyhemoglobin. In contrast, hemoglobin binds to carbon dioxide, forming carbaminohemoglobin.
Figure 1: HBA1
Moreover, the hemoglobin molecule consists of four protein subunits. Therefore, it is a tetramer. The type of subunits in the molecule determines the type of hemoglobin. Generally, the most common type of hemoglobin in adults is hemoglobin A (α2β2), which comprises two α and two β subunits. However, the type of hemoglobin in infants is hemoglobin F (α2γ2), composing two α chains and two γ chains. Meanwhile, each subunit of hemoglobin contains a non-protein, prosthetic heme group, which consists of iron in a heterocyclic ring of porphyrin.
Furthermore, the reduced amounts of hemoglobin cause anemia, decreasing the binding of oxygen into red blood cells. Genetic defects cause hemoglobin molecules with abnormal structures, resulting in hemoglobinopathies. Also, nutritional deficiencies, blood loss, bone marrow problems, etc., cause low hemoglobin levels.
What is the Alpha Chain in Hemoglobin
Alpha chain in hemoglobin or alpha 1 is a hemoglobin protein encoded by the HBA1 gene. The human alpha globin is a gene cluster located on chromosome 16. The length of the gene is 30 kb. It includes seven loci: 5′- zeta – pseudozeta – mu – pseudoalpha-1 – alpha-2 – alpha-1 – theta – 3′. Here, alpha-2 (HBA2) and alpha-1 (HBA1) coding sequences are identical. However, introns and 5′ untranslated regions are slightly different. Also, significant differences occur over the 3′ untranslated regions.
Furthermore, deletions of the alpha genes result in alpha thalassemia.
What is the Beta Chain in Hemoglobin
Beta chain in hemoglobin or beta globin is a globin protein encoded by the HBB gene. It is 147 amino acids long. Its molecular weight is 15,867 Da. Also, the HBB gene is located in the chromosome 11. Further, it is a gene cluster containing 5′ – epsilon – gamma-G – gamma-A – delta – beta – 3′. Mutations in the HBB gene result in sickle cell disease and beta-thalassemia.
Figure 2: HBB
Similarities Between Alpha and Beta Chains in Hemoglobin
- Alpha and beta chains in hemoglobin are two polypeptide chains that occur in hemoglobin.
- They are gene clusters.
- Each hemoglobin molecule contains two alpha and beta chains.
- Hemoglobin transports oxygen from the lungs to the tissue.
Difference Between Alpha and Beta Chains in Hemoglobin
Definition
The alpha chain in hemoglobin refers to a hemoglobin protein that is encoded by the HBA1 gene in humans. In contrast, the beta chain in hemoglobin refers to a globin protein coded for by the HBB gene.
Encoded by
The alpha chain in hemoglobin is encoded by the HBA1 gene on chromosome 16, while the HBB gene on human chromosome 11 encodes the beta chain in hemoglobin.
Number of Amino Acids
The alpha chain in hemoglobin contains 141 amino acids, while the beta chain in hemoglobin contains 146 amino acids.
FAQ: Alpha and Beta Chain in Hemoglobin
What is the difference between alpha and beta thalassemia?
Reduced or absent synthesis of alpha globin chains results in alpha thalassemia. In contrast, reduced or absent synthesis of beta-globin chains results in beta-thalassemia.
Does hemoglobin have two alpha and two beta chains?
Adult hemoglobin A contains two alpha and two beta chains. In comparison, hemoglobin A2 includes two alpha and two delta chains.
What are alpha vs. beta-globin genes?
The alpha-globin gene is located in the telomeric region of chromosome 16. In comparison, the beta-globin gene is located on chromosome 11p15.
Conclusion
In brief, alpha and beta chains in hemoglobin are two types of polypeptide chains that occur in hemoglobin. The alpha chain in hemoglobin contains 141 amino acids. Also, it is encoded by the HBA1 gene. In comparison, the beta chain in hemoglobin contains 146 amino acids. However, it is encoded by the HBB gene. Therefore, the main difference between the alpha and beta chains in hemoglobin is the number of amino acids in the polypeptide chain.
References:
- Hemoglobin A. Hemoglobin A – an overview | ScienceDirect Topics. (n.d.-a).
Image Courtesy:
- “Protein HBA1 PDB 1a00” By Emw – Own Work (CC BY SA 3.0) via Commons Wikimedia
- “Protein HBB PDB 1a00″ By Emw (CC BY SA 3.0) via Commons Wikimedia
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