CHAPTER 24: Unit 15. Carbon Atoms Skeleton from Amino Acids Transamination
Lesson Progress
0% Complete
| The fate of carbon skeleton of amino acid is illustrated in the figure below: |
 |
| Reference: https://chem.libretexts.org/Courses/University_of_South_Carolina_-_Upstate/USC_Upstate%3A_CHEM_U109_-_Chemistry_of_Living_Things_(Mueller)/16%3A_Energy_Metabolism/16.7%3A_Stage_II_of_Protein_Catabolism |
| The fate of carbon skeleton of amino acid undergoes conversion as intermediate that enters the citric acid cycle. In the process the amino group removal by the transamination. The rest of the acid; the α – keto acid remains in this process which enters into different reaction pathways. Example of this reaction is the conversion of phenylalanine to fumarate and acetoacetate through six different reaction. The fumarate then enters into the citric acid cycle and the acetoacetate is converted to acetoacetyl coenzyme A abbreviated as CoA before it enters the citric acid cycle.Gluconeogenesis is the process by which the amino acids are converted into glucose. Such amino acids undergoing gluconeogenesis are called glucogenic amino acids which are converted to acetoacetyl CoA or acetyl CoA.The acetoacetyl CoA or acetyl CoA are used for the ketone bodies synthesis. The amino acids formed from this process are ketogenic amino acids. Only leucine and lysine are the only amino acids that are considered to be ketogenic acids.The citric acid cycle is illustrated in the figure below: |
 |
| Reference: http://www.biosciencenotes.com/citric-acid-cycle |
| The Citric Cycle: http://www.biosciencenotes.com/citric-acid-cycle/ |
| The citric acid cycle (also called Kreb’s cycle or tricarboxylic acid or TCA cycle) supplies the energy to the body. The name TCA cycle is used because tricarboxylic acids (citrate, cis-aconitate, and isocitrate) are produced during the Kreb’s cycle..Kreb’s cycle is an aerobic metabolism. .In the citric acid cycle, the oxidation occurs of Acetyl CoA to CO2 and H2O. Furthermore, ATP is produced in this cycle via oxidation reactions of carbohydrates, fats, and amino acids. The Kreb’s cycle provides energy and several intermediate needed for the amino acids synthesis as well as glucose, heme, etc. The enzymes of TCA cycle are located in the matrix of mitochondria |
| In short the citric cycle (Kreb’s Cycle) involves a two-carbon acetyl CoA with a 4C oxaloacetate to produce a 3C tricarboxylic acid, citrate which then further react via oxidation of 2C to CO2 and oxaloacetate formation. |
| The steps of citric cycle are given below in the figure below: |
 |
| Reference: http://www.biosciencenotes.com/citric-acid-cycle/ |
The videos below illustrate the Citric Acid Cycle: