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”’Transamination”’ is a chemical reaction that transfers an [[amino group]] from ”an amino acid to an α-keto acid”. |
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In [[biochemistry]], the process occurs extensively during [[amino acid synthesis]] an is catalyzed by [[transaminase]] [[Transaminase|(aminotransferases)]] , which require the cofactor pyridoxal phosphate (PLP) , and an [[Ketoacid|α-keto]] [[Ketoacid|acid]] as the acceptor of the amino group. |
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== The Role of Specific Tissues and Organs in Transamination == |
== The Role of Specific Tissues and Organs in Transamination == |
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The ”’liver”’ is the primary site of transamination. After a protein is digested into its monomers, amino acids, they are transported to the liver. In the cytoplasm of a liver cell, the amino groups from many amino acids are transferred to α-ketoglutarate, forming glutamate (transamination reaction) <ref name=”:0″>{{Cite web|title=18.6: The Catabolism of Proteins|url=https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Map%3A_Essential_Organic_Chemistry_(Bruice)/18%3A_The_Organic_Chemistry_of_Metabolic_Pathways/18.6%3A_The_Catabolism_of_Proteins|website=Chemistry LibreTexts|date=2014-08-30|access-date=2025-11-28|language=en}}</ref>. Through transamination, the amino groups from different amino acids are combined into glutamate, reducing the need for multiple enzymes in subsequent elimination or biosynthetic processes. After this transamination reaction, glutamate is transported into the mitochondria, where glutamate dehydrogenase removes the amino group (deamination)<ref name=”:0″ />. The ammonium can then react with bicarbonate to form carbamoyl phosphate, which enters the [[urea cycle]]. Aspartate aminotransferase is also in the liver. This enzyme catalyzes a unique reaction where a-ketoglutarate is not the carrier molecule. Another carrier molecule, oxaloacetate, is used <ref>{{Citation|edition=3rd|title=Aminotransferases|url=http://www.ncbi.nlm.nih.gov/books/NBK425/|publisher=Butterworths|work=Clinical Methods: The History, Physical, and Laboratory Examinations|date=1990|access-date=2025-11-28|place=Boston|isbn=978-0-409-90077-4|pmid=21250265|first=David H.|last=Vroon|first2=Zafar|last2=Israili|editor-first=H. Kenneth|editor-last=Walker|editor2-first=W. Dallas|editor2-last=Hall|editor3-first=J. Willis|editor3-last=Hurst}}</ref>. Thus, glutamate transfers an amino group to oxaloacetate, forming the amino acid aspartate and a-ketoglutarate. Aspartate can enter the urea cycle. |
The ”’liver”’ is the primary site of transamination. After a protein is digested into its monomers, amino acids, they are transported to the liver. In the cytoplasm of a liver cell, the amino groups from many amino acids are transferred to α-ketoglutarate, forming glutamate (transamination reaction) <ref name=”:0″>{{Cite web|title=18.6: The Catabolism of Proteins|url=https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Map%3A_Essential_Organic_Chemistry_(Bruice)/18%3A_The_Organic_Chemistry_of_Metabolic_Pathways/18.6%3A_The_Catabolism_of_Proteins|website=Chemistry LibreTexts|date=2014-08-30|access-date=2025-11-28|language=en}}</ref>. Through transamination, the amino groups from different amino acids are combined into glutamate, reducing the need for multiple enzymes in subsequent elimination or biosynthetic processes. After this transamination reaction, glutamate is transported into the mitochondria, where glutamate dehydrogenase removes the amino group (deamination)<ref name=”:0″ />. The ammonium can then react with bicarbonate to form carbamoyl phosphate, which enters the [[urea cycle]]. Aspartate aminotransferase is also in the liver. This enzyme catalyzes a unique reaction where a-ketoglutarate is not the carrier molecule. Another carrier molecule, oxaloacetate, is used <ref>{{Citation|edition=3rd|title=Aminotransferases|url=http://www.ncbi.nlm.nih.gov/books/NBK425/|publisher=Butterworths|work=Clinical Methods: The History, Physical, and Laboratory Examinations|date=1990|access-date=2025-11-28|place=Boston|isbn=978-0-409-90077-4|pmid=21250265|first=David H.|last=Vroon|first2=Zafar|last2=Israili|editor-first=H. Kenneth|editor-last=Walker|editor2-first=W. Dallas|editor2-last=Hall|editor3-first=J. Willis|editor3-last=Hurst}}</ref>. Thus, glutamate transfers an amino group to oxaloacetate, forming the amino acid aspartate and a-ketoglutarate. Aspartate can enter the urea cycle. |
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The ”’skeletal muscles”’ are another site of transamination. Pyruvate is plentiful in muscle due to extensive glycolysis. Amino groups in skeletal muscles are transferred to a product of glycolysis, pyruvate, forming alanine <ref>{{ |
The ”’skeletal muscles”’ are another site of transamination. Pyruvate is plentiful in muscle due to extensive glycolysis. Amino groups in skeletal muscles are transferred to a product of glycolysis, pyruvate, forming alanine <ref>{{|title= and |url=https://..com/==|=|access-date=2025-11-28}}</ref>. This transamination reaction is catalyzed by alanine aminotransferase. Alanine is then transported to the liver, where it is converted back into Pyruvate (used for [[gluconeogenesis]]) by transferring its amino group to α-ketoglutarate, forming glutamate <ref>{{|title= |url=https://..com/==|=|access-date=2025-11-28}}</ref>. Simultaneously, glucose is being transported from the liver (where it’s more abundant due to gluconeogenesis) to the muscle, where it is consumed. This is the glucose-alanine cycle. |
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Latest revision as of 05:22, 28 November 2025
Transamination is a chemical reaction that transfers an amino group from an amino acid to an α-keto acid.
In biochemistry, the process occurs extensively during amino acid synthesis an is catalyzed by transaminase (aminotransferases) , which require the cofactor pyridoxal phosphate (PLP) , and an α-keto acid as the acceptor of the amino group.
The Role of Specific Tissues and Organs in Transamination
[edit]
The liver is the primary site of transamination. After a protein is digested into its monomers, amino acids, they are transported to the liver. In the cytoplasm of a liver cell, the amino groups from many amino acids are transferred to α-ketoglutarate, forming glutamate (transamination reaction) [1]. Through transamination, the amino groups from different amino acids are combined into glutamate, reducing the need for multiple enzymes in subsequent elimination or biosynthetic processes. After this transamination reaction, glutamate is transported into the mitochondria, where glutamate dehydrogenase removes the amino group (deamination)[1]. The ammonium can then react with bicarbonate to form carbamoyl phosphate, which enters the urea cycle. Aspartate aminotransferase is also in the liver. This enzyme catalyzes a unique reaction where a-ketoglutarate is not the carrier molecule. Another carrier molecule, oxaloacetate, is used [2]. Thus, glutamate transfers an amino group to oxaloacetate, forming the amino acid aspartate and a-ketoglutarate. Aspartate can enter the urea cycle.
The skeletal muscles are another site of transamination. Pyruvate is plentiful in muscle due to extensive glycolysis. Amino groups in skeletal muscles are transferred to a product of glycolysis, pyruvate, forming alanine [3]. This transamination reaction is catalyzed by alanine aminotransferase. Alanine is then transported to the liver, where it is converted back into Pyruvate (used for gluconeogenesis) by transferring its amino group to α-ketoglutarate, forming glutamate [4]. Simultaneously, glucose is being transported from the liver (where it’s more abundant due to gluconeogenesis) to the muscle, where it is consumed[4]. This is the glucose-alanine cycle.
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- ^ a b “18.6: The Catabolism of Proteins”. Chemistry LibreTexts. 2014-08-30. Retrieved 2025-11-28.
- ^ Vroon, David H.; Israili, Zafar (1990), Walker, H. Kenneth; Hall, W. Dallas; Hurst, J. Willis (eds.), “Aminotransferases”, Clinical Methods: The History, Physical, and Laboratory Examinations (3rd ed.), Boston: Butterworths, ISBN 978-0-409-90077-4, PMID 21250265, retrieved 2025-11-28
- ^ Bhagavan, N.V. (2002), “Protein and Amino Acid Metabolism”, Medical Biochemistry, Elsevier, pp. 331–363, doi:10.1016/b978-012095440-7/50019-6, ISBN 978-0-12-095440-7, retrieved 2025-11-28
- ^ a b Litwack, Gerald (2022), “Metabolism of Amino Acids”, Human Biochemistry, Elsevier, pp. 403–440, doi:10.1016/b978-0-323-85718-5.00020-0, ISBN 978-0-323-85718-5, retrieved 2025-11-28
