Protein Metabolism
Describe the physiology and biochemistry of
fat, carbohydrate andprotein metabolism
Essential amino acids cannot be produced by transamination - they must be supplied in the diet.
Metabolism
Protein catabolism involves the deamination of amino acids. Deamination can occur in one of two ways:
- Oxidative deamination
Hepatic deamination, removing the amino group to create a ketoacid and ammonia. Ammonia produced in the liver enters the urea cycle and becomes urea, which requires 3 ATP. - Transamination
Amino group is transferred by aminotransferases to another amino acid or a ketoacid to produce:- Keto acids, which:
- Enter the citric acid cycle and produce ATP
- Get converted to glucose or fatty acids
- Amino groups
- Enter the urea cycle and become urea
- Keto acids, which:
Footnotes
Ammonia can also be produced in the kidney by the deamination of glutamate in the kidney. In this instance:
- It is eliminated directly in urine as ammonium
- Does not enter the urea cycle
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References
- Chambers D, Huang C, Matthews G. Basic Physiology for Anaesthetists. Cambridge University Press. 2015.