Biosynthesis of amino acid (essential and non essential)

Biosynthesis of amino acid, Biosynthesis of essential amino acids, Biosynthesis of non essential amino acids

1. Biosynthesis of
amino acids
AnamSharif
Lecturer (University of Okara)

2. WHAT ARE
AMINO ACIDS?

3. An amino acid is organic molecule that contains a carboxyl group,
–COOH ,an amine group, –NH2as well as R-group.
Amino acids derived from proteins have the amino group on the
alpha (a) carbon i.e; the carbon atom next to the carboxyl group.
The amino acids differ in the nature of R group attached to a
carbon atom. The nature of R-group determines the properties of
proteins.
The major key elements of amino acids are carbon,hydrogen,
nitrogen, oxygen.

4. •Aminoacidsarethestructuralunitsthatmakeupproteins.
Theyjointogethertoformshortpolymerchainscalled
peptidesorlongerchainscalledeitherpolypeptidesor
proteins.
•Thesepolymersarelinearandunbranched,witheach
aminoacidwithinthechainattachedtotwoneighboring
aminoacids.
•Inproteins,almostallofthesecarboxylandaminogroups
arecombinedthroughpeptidelinkageand,ingeneral,are
notavailableforchemicalreactionexceptforhydrogen
bondformation.

5. Tpyesof Amino acid based
on nutritional requirements :
1.Essential amino acids:
Essential amino acids unable to synthesize by body as They
must obtained from food and their sources are plants and
microbes.
Examples :
The essential amino acids are: histidine, isoleucine, leucine,
lysine, methionine, phenylalanine, threonine, tryptophan,
and valine.

6. 2. Non essential amino acids :
Non essential amino acid if they are not supplied in our diet
we can synthesized that. Most of the amine group come
from glutamate and glutmine. Some of them synthesize from
essential amino acid .
e.gtyrosine is synthsizefrom phenylalanine
and Cysteine depends on methionine
Examples:
The nonessential amino acids: Arginine, Alanine, asparagine,
aspartic acid, cysteine, glutamic acid, glutamine, glycine,
proline, serine, and tyrosine.

7. •Amino acids precursors are intermediates
in glycolysis, the citric acid cycle, or the
pentose phosphate pathway . They are
used to make nucleotide.
•Histidine comes from Ribose 5-phosphate
that is product of pentose phosphate
pathway.
•Serine comes from 3-phosphoglycerate
and from serine we can make more amino
acids like glycine and cysteine.
•Tryptophaneand tyrosine comes from
phosphoenolepyruvate.
•Pyruvate used to make alanine,valine,
leucine and isoleucine.

8. •we can make aspartate
from oxaloacetate and we
can use aspartate to make
other amino acids like
aspargine, methionine,
threonine and lysine.
•Glutamate is synthesized
from @ ketoglutarate
.And from glutamate we
can make more amino
acids like glutamaine,
prolineand arginine .

9. SYNTHESIS
OF
NON-ESSENTIAL
AMINO ACIDS

11. Glutamate Synthesis from ketoglutarate
•Glutamateissynthesizedbythereductiveaminationof2-oxoglutarate(α-
ketoglutarate)catalyzedbyglutamatedehydrogenase(GDH);itisthusa
nitrogen-incorporatingreaction.
•Glutamatedehydrogenaserepresentsanimportant"gateway"enzymeinthat
itcancatalyzereactionsintwodifferentdirectionsdependentuponoverall
cellularenergyandmetabolicneeds.
•Whenenergyandcarbonlevelsarehighglutamatecanincorporatenitrogen
(fromNH
4
+
)into2-oxoglutarate.whichisdrivenbytheincreasedlevelsof
NADPHgeneratedfromoxidationofglucoseinthePentosePhosphate
Pathway.
•whenenergylevelsarereducedglutamatecanbeoxidativelydeaminatedin
theoppositedirectionallowing2-oxoglutaratetobeutilizedintheTCA
cycleforproductionofenergy.

12. GlumatineSynthesis From Glutamate
•Glutamine is synthesized from glutamate via the action of glutamine
synthetase. The synthesis of glutamine is a two-step one in which
glutamate is first "activated" to agema-glutamylphosphate
intermediate, followed by a reaction in which NH
3displaces the
phosphate group

14. Aspartate Synthesis From Oxaloacetate
•Aspartate is synthesize by the transfer of a ammonia group from
glutamate to oxaloacetate. Aspartate can be formed in a transamination
reaction. The transamination reaction is catalyzed by aspartate
transaminase, AST. This reaction uses the α-ketoacid oxaloacetate as the
amino acceptor and glutamate as the primary amino group donor
=

15. Synthesis of Asparagine from Aspartate
•Asparagine is synthesized from aspartate via an amidotransferasereaction
catalyzed by asparagine synthetase.

17. Alanine synthesis from Pyruvate
There are two main pathways to production of muscle alanine:
directly from protein degradation, and via the transamination of
pyruvate by alanine transaminase (ALT).

19. Synthesis of serine
•Serine can be derived from the glycolytic intermediate, 3-
phosphoglycerate, in a three-step reacitonpathway.
•The first reaction is catalyzed by phosphoglyceratedehydrogenase
(PHGDH) in which oxidation of the hydroxyl group of 3-
phosphoglycerate by NAD+ to produce3-phosphohydroxy
pyruvate.
•The second reaction is a simple transamination catalyzed by
phosphoserineaminotransferase (PSAT) which utilizes glutamate
as the amino donor and releases 2-oxoglutarate (α-ketoglutarate).
•The last step in the reaction pathway is catalyzed by
phosphoserinephosphatase (PSPH).Finally, hydrolysis and
removal of the phosphate group yields serine.

21. Synthesis of Glycine from serine
The main pathway to glycine is a one-step reversible reaction
catalyzed by serine hydroxymethyltransferase(SHMT). This enzyme
is a member of the family of one-carbon transferasesand is also
known as glycine hydroxymethyltransferase. This reaction involves
the transfer of the hydroxymethylgroup from serine to the cofactor
tetrahydrofolate(THF), producing glycine and
N
5
,N
10
-methylene-THF.

22. SYNTHESIS
OF
ESSENTIAL
AMINO
ACIDS

23. SynthesisofEssentialAminoAcids
Thesyntheticpathwaysfortheessentialaminoacidsare:
(1)presentonlyinmicroorgansims
(2)considerablymorecomplexthanfornonessentialaminoacids
(3)usefamiliarmetabolicprecursors
(4)showspeciesvariation
Forpurposesofclassification,considerthefollowing
4"families"whicharebaseduponcommonprecursors:
(1)AspartateFamily:lysine,methionine,threonine
(2)PyruvateFamily:leucine,isoleucine,valine
(3)AromaticFamily:phenylalanine,Tyrosine,Tryptophan
(4)Histidine

24. Synthesis of valineand leucine
•The pathway of valinebiosynthesis is a four-step pathway.
•Acetolactatesynthase transfers the acyl group of pyruvate to
another molecule of pyruvate, forming acetolactate. This is
the 1
st
step in the biosynthesis of the amino acids valineand
leucine
•In the 2
nd
step acetolactateis converted into 2,3-di
hydroxyisovaleratein the presence of acetohydroxyacid
reductoisomerase.
•In 3
rd
step Dihydroxyaciddehydratase enzyme convert
2,3-di hydroxyisovalerateinto 2-keto-isovalerate.
•In 4
th
step 2-keto-isovalerate conevtedinto Valineand
leucine with the help of transferaseenzymes.

25. Synthesis of phenylalanine and tyrosine
•Analternativepathwayofphenylalanineandtyrosinebiosynthesisfromchorismate(is
animportantbiochemicalintermediateinplantsandmicroorganisms)hasbeen
characterizedinbacteria,fungiandhigherplants.
•Thealternativepathwaycalledthepretyrosine(orarogenate)pathwayinvolves
transaminationofprephenatetoformpretyrosine(arogenate).Tyrosineand
phenylalaninecanthenbeformedfromarogenatebyarogenatedehydrogenaseand
arogenatedehydratase,respectively.

26. Dehydratasesare a group of lyaseenzymes
that form double and triple bonds in a
substrate through the removal of water
Dehydrogenasesare a group of biological
catalysts (enzymes) that mediate in
biochemical reactions removing hydrogen
atoms [H] instead of oxygen [O]