amino acid essential and non- essential amino acid

1. METABOLISM OF ESSENTIAL AND
NON ESSENTIAL AMINO ACIDS
PREPARED BY
MUBASHRA GUL

3. ESSENTIAL & NON ESSENTIAL AMINO ACIDS
 Nonessential amino acids can be synthesized in
sufficient amounts from the intermediates of metabolism
or, as in the case of cysteine and tyrosine, from essential
amino acids.
 Essential amino acids cannot be synthesized (or
produced in sufficient amounts) by the body and,
therefore, must be obtained from the diet in order of
normal protein synthesis to occur.
 Genetic defects in the pathways of amino acid
metabolism can cause serious disease.

5. METABOLISM OF AMINO ACIDS
 Amino acids are locked from being metabolized until their
amino group is removed. Carbon skeleton is metabolized
afterwards to give energy.
 Amino group is removed by
1.Transamination
2. Deamination
1.Transamination: (a chemical reaction that transfers an
amino group to a ketoacid to form new amino acids)
The first step in the catabolism of most amino acids is the
transfer of their α-amino group to α-ketoglutarate. The
products are an α-keto acid (derived from the original
amino acid) and glutamate. Glutamate produced by
transamination can be oxidatively deaminated.
 Synthesis of non essential amino acids

6.  The reaction is catalyzed by a family of enzymes called
aminotransferases (Alanine aminotransferase (ALT) and
Aspartate aminotransferase (AST) are important
transaminases. These enzymes are found in the cytosol
and mitochondria of cells through out the body).
 All amino acids, with the exception of lysine and
threonine, participate in transamination at some point in
their catabolism.
 These two amino acids lose
their α-amino groups by
deamination.

7. 2. Oxidative deamination of aminoacids
 Oxidative deamination by glutamate dehydrogenase
results in the liberation of the amino group as free
ammonia (NH3).
 These reactions occur primarily in the liver and kidney.
 The ammonia is then transferred to liver to form urea
which is the major disposal form of amino groups
derived from amino acids, and accounts for about 90%
of the nitrogen-containing components of urine.

8. PRODUCTS OBTAINED FROM AMINOACID CARBON
SKELETON
 Seven products are obtained from degradation of carbon
skeletons of 20 amino acids
 1. Pyruvate
 2. Acetyl CoA
 3. Acetoacetate
 4. Ketoglutarate
 5. Succinyl CoA
 6. Fumarate
 7. Oxaloacetate

9.  Amino acids can be classified as glucogenic, ketogenic, or
both based on which of the seven intermediates are
produced during their catabolism.
Glucogenic amino acids
Amino acids whose catabolism yields pyruvate or one of the
intermediates of the citric acid cycle are termed glucogenic.
These intermediates are substrates for gluconeogenesis.
Ketogenic amino acids
Amino acids whose catabolism yields either aceto acetate
or one of its precursors (acetyl CoA or aceto acetyl CoA) are
termed ketogenic. Leucine and lysine are the only
exclusively ketogenic amino acids found in proteins. Their
carbon skeletons are not substrates for gluconeogenesis
and cannot give rise to the net formation of glucose.

10.  CATABOLISM OF THE CARBON SKELETONS OF AMINO
ACIDS
The pathways by which amino acids are catabolized are
conveniently organized according to which one (or more) of
the seven intermediates listed above is produced from a
particular amino acid.
1. Amino acids which form Oxaloacetate
 Asparagine(N.E.A) is hydrolyzed by
asparaginase, liberating ammonia
and aspartate. Aspartate loses its
amino group by transamination to
form oxaloacetate.
 Aspargine
 Aspartate

11. 2. AMINO ACIDS WHICH FORM Α-KETOGLUTARATE
VIA GLUTAMATE
 Glutamine
 Proline
 Arginine
 Histidine
 Glutamate

12. 3. AMINO ACIDS WHICH FORM PYRUVATE
 Alanine, Serine, Glycine, Cystine, Threonine

13. 4. AMINO ACIDS WHICH FORM FUMARATE AND
ACETOACETATE
 Phenyl alanine and Tyrosine
 They are both glucogenic and ketogenic
 Inherited deficiency of their enzymes leads to
phenylketonuria (mental disability), alkaptonuria* and
albinism
*(body cannot process the amino
acids phenylalanine and
tyrosine, which occur in protein.)

14. 5.AMINO ACID WHICH FORM SUCCINYL COA
 Methionine is one of four amino acids that form succinyl
CoA. This sulfur-containing amino acid deserves special
attention because it is converted to S-adenosyl methionine
(SAM),
 These amino acids are , Methionine, valine, isoleucine,
and threonine

16. 6. AMINO ACIDS WHICH FORM ACETYL COA OR
ACETOACETYL COA
 Leucine, Isoleucine, Lysine and Tryptophan
 They are ketogenic as Acetyl CoA/Acetoacetyl CoA cannot
participate in gluconeogenesis
 Essential amino acids which are branched chain (Leucine,
isoleucine, valine) are metabolized by similar pathway.

17. CATABOLISM OF THE BRANCHED-CHAIN
AMINO ACIDS
 The branched-chain amino acids, isoleucine,
leucine, and valine, are essential amino acids. In
contrast to other amino acids, they are metabolized
primarily by the peripheral tissues (particularly
muscle), rather than by the liver.
1.Transamination
2.Oxidative decarboxylation
3.Dehydrogenation

20. Summary of the metabolism of amino acids in humans. Genetically determined enzyme
deficiencies are summarized in white boxes.