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The Metabolic Pathway of Shikimic Acid Aromatic Amino Acids Phenolic Compounds. Jan Michael O. Santos Philippine Normal University College of Science Department of Physical Sciences. Outline of Discussion. 1 . Shikimic Acid Pathway Origin of Shikimic Acid Starting Material - PowerPoint PPT Presentation
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The Metabolic Pathway of
Shikimic Acid Aromatic Amino AcidsPhenolic Compounds
Jan Michael O. SantosPhilippine Normal University
College of ScienceDepartment of Physical Sciences
Outline of Discussion1. Shikimic Acid Pathway
a. Origin of Shikimic Acidb. Starting Material c. Enzymes d. Pathway- Mechanisme. Product
2. Aromatic Amino Acids
a. What are the Aromatic Amino Acidsb. Starting Materialc. Enzymes d. Pathway- Mechanisme. Products
3. Phenolic Compounds
a. What are Phenolic Compoundsb. Starting Materialc. Enzymesd. Pathway- Mechanisme. Products
DEFINITION OF TERMS1. Shikimic acid or shikimate: is an important
biochemical metabolite in plants and microorganisms.
2. Aromatic compound: is a hydrocarbon with alternating double bonds and single bonds between carbon atoms
3. Amino acids: are molecules containing an amine group, a carboxylic acid group and a side chain (specific)
4. Phenolic Compounds: are a large and diverse group of molecules, which includes many families of aromatic secondary metabolite in plants.
5. Enzymes: are group of molecules that serve as a catalyst with a high degree of specificity for a certain substrate or class of substrates. It can only act on one substrate or on a family of structurally similar substrates.
MAJOR ENZYMES
1. Synthase: Joints two molecules together w/o hydrolyzing a pyrophosphate bond.
2. Dehydratase: Removes water to create a double bond
3. Dehydrogenase: Removes hydrogen atom from its substrate
4. Kinase: Transfer a phosphate group from a high-energy phosphate compound such as ATP to its substrate.
SHIKIMIC ACID
Where this came from?
Shikimi Illicium anisatum
Shikimic acid is a precursor for:
1. Aromatic amino acids phenylalanine and tyrosine
2. Indole, and indole derivatives and a.a.a tryptophan
3. Alkaloids 4. Phenylpropanoids, flavonoids,
tannins, and lignins.
FORMATION OF SHIKIMIC ACIDStarting materials1st: Pyruvate to Phospoenolpyruvate
FORMATION OF SHIKIMIC ACID2nd : Erthryrose-4-phosphate
FORMATION OF SHIKIMIC ACID
Analyze this reaction, what are the other materials involve?
FORMATION OF SHIKIMIC ACID
3-deoxy-D-arabinoheptulosonate 7-phosphate (DAHP) synthase is the first enzyme in a series of metabolic reactions known as the shikimate pathway.
Since it is the first enzyme in the shikimate pathway, it controls the amount of carbon entering the pathway.
FORMATION OF SHIKIMIC ACID
OH PO
OO C
CH2
COOH
O
OH HCH2
OHH
H
PO
H+
HO
H
erythrose-4-phosphate
phosphoenol pyruvate
O CCH2
COOH
OH
OH H
OHH
H
CH2OP
O
O
OH
O CCH2
COOH
OH
OH H
CH2H
OH
H+
OOH
OH
H
OHCOOH
OOH
OH
COOH
OHOH
OH
COOH
shikimic acid
NADPH
H+
FORMATION OF SHIKIMIC ACID
B:
FORMATION OF SHIKIMIC ACID
3-dehydroquinate synthase is the second enzyme of the shikimate pathway. It catalyzes the elimination of phosphate from DAHP to generate 3-dehydroquinate (DHQ).
FORMATION OF SHIKIMIC ACID
FORMATION OF SHIKIMIC ACID
3-Dehydroquinate Dehydratase (DHQD) catalyzes the third step of the shikimate pathway, dehydration of 3-dehydroquinate to 3-dehydroshikimate.
FORMATION OF SHIKIMIC ACID
FORMATION OF SHIKIMIC ACID
Shikimate-5-Dehydrogenase (SDH) The fourth step of the shikimate pathway is the reduction of DHS to shikimate. the reaction is catalyzed by an NADP-dependent shikimate dehydrogenase (SHD)
FORMATION OF SHIKIMIC ACID
FORMATION OF SHIKIMIC ACID
FORMATION OF SHIKIMIC ACID
Shikimate Kinase (SK)- In the fifth step of the shikimate pathway, shikimate kinase catalyzes the specific phosphorylation of the 3-hydroxyl group of D-shikimate to yield shikimate 3-phosphate using ATP as a co-subtrate
FORMATION OF SHIKIMIC ACID
FORMATION OF SHIKIMIC ACID
5-Enolpyruvylshikimate 3-Phosphate Synthase (EPSPS) is the sixth enzyme of the shikimate pathway. It catalyzes the reversible formation of 5-enolpyruvyl-shikimate-3- phosphate (EPSP) from shikimate 3-phosphate and PEP.
FORMATION OF SHIKIMIC ACID
FORMATION OF SHIKIMIC ACID
Chorismate Synthase (CS) The seventh and final step in the main trunk of the shikimate pathway is the trans-1,4 elimination of phosphate from EPSP to yield chorismate
FORMATION OF SHIKIMIC ACID
In this reaction, the second of the three double bonds of the benzene ring is introduced. The reaction is catalyzed by chorismate synthase and requires reduced flavin for activity even though the overall reaction is redox neutral.
FORMATION OF SHIKIMIC ACID
SHIKIMIC ACID TO AROMATIC ACID
The seven-step shikimate pathway links the metabolism of carbohydrates to the biosynthesis of aromatic amino acids and many aromatic secondary metabolites, including tetrahydrofolate and ubiquinone.
Aromatic Amino Acids
F
Y
W
Aromatic Amino Acids 1. What are aromatic amino acids?
Aromatic Amino Acids are amino acids that include an aromatic ring.Example includes:Phenylalanine, Tryptophan, Histidine, Tyrosine (but only F, W, Y can be synthesized by Shikimate pathway)
The Aromatic Family
In plants and microorganism:Phe, Tyr, and Trp
Precursors are: PEP ERYTHROSE-4-PHOSPHATE CHORISMATE
The Starting Material
CHORISMATE
EnzymesIsomerase is an enzyme that catalyzes the structural rearrangement of isomers.Mutase: catalyzes the shifting of a functional group from one position to another within the same molecule.
Transferase: catalyzes the transfer of a functional group (methyl or phosphate)from one molecule to another
The Pathway
The MechanismsFrom Chorismate to Prephenate
Chorismate mutase catalyzes the Claisen rearrangement of chorismate ion
to prephenate ion
The Mechanisms
What is Claisen Rearrangement?
Claisen Rearrangement is a powerful carbon-carbon bond-forming chemical reaction discovered by Rainer Ludwig Claisen.
In NMR spectrum (chair conformation)
O
-O2C
OH
COO-
13.6
Chair and Boat Conformation
O COO-3H H
OH
COO-
O
-OOCH
3H
OH
COO-
OH
O
COO-
COO-H3H
OH
3HH
COO-O
-OOC
Z-13.7
pro-S
chair
pro-R
boat
Z-13.7
13.8
13.9
A
B
OVER-ALL STRUCTURE
COO-
HO
O COO-
CH2
HO
-OOC CH2 C
O
COO-
13.213.1
12
3
45
6
78
9 12
34
5
6
7
8
9
CHORISMATE PREPHENATE
Phenylalanine Biosynthesis
Prephenate dehyrdatase to Phenylpyruvate
The Mechanism
Phenylpyruvate to Phenylalanine
Phenylalanine aminotransferase catalyze this reaction
The Mechanisms
Prephenate to Phenylpyurvate to Phenylalanine
SOURCES OF ESSENTIAL AMINO ACIDS
Phenylalanine
Tyrosine Biosynthesis
The Mechanism
Prephenate to p-Hydroxyphenylpyruvate
Prephenate dehydrogenase catalyzed this reaction.
The Mechanism
p-Hydroxyphenylpyruvate to Tyrosine
Tyrosine aminotransferase catalyzed this reaction
SOURCES OF ESSENTIAL AMINO ACIDSTyrosine
OVER-ALL PATHWAY
Tryptophan Biosynthesis
The Mechanism
This reaction is catalyzed by
athranilate synthase
The Mechanism
This reaction is catalyzed by athranilate
phosphoribosyl transferase
The Mechanism
This reaction is catalyzed by
phosphoribosyl athranilate isomerase.
The Mechanism
This reaction is catalyzed by
indole-3-glucerol
phosphate synthase.
This reaction is catalyzed by tryptrophan
synthase
OVER-ALL PATHWAY
SOURCES OF ESSENTIAL AMINO ACIDS
Tryptophan
SOURCES OF ESSENTIAL AMINO ACIDS
Phenylalanine
SOURCES OF ESSENTIAL AMINO ACIDSTyrosine
SOURCES OF ESSENTIAL AMINO ACIDS
Tryptophan
AMINO ACID DEGRADATION INTERMEDIATES
CO2
CO2
Pyruvate
Acetyl-CoA Acetoacetate
Citrate
Isocitrate
a-ketoglutarateSuccinyl-CoA
Fumarate
Oxaloacetate
CitricAcid
Cycle
CO2
Glucose
Ala SerCys Thr*Gly Trp*
Ile*Leu•
Lys•
Thr*
Leu• Trp*Lys• Tyr*Phe*
AsnAsp
AspPhe*Tyr*
Ile*MetVal
Arg HisGlu ProGln
Glucogenic
Ketogenic
* Both Glucogenic and Ketogenic• Purely Ketogenic
PHENOLIC ACID
PHENOLICSThese are the class of natural occuring compound with one or more phenolic compounds or benzene ring with –OH group.
Quercetin, a typical flavonoid, is a natural phenol
BIOSYNTHESIS OF PHENOLICS
Most of the natural phenols are derived from secondary plant metabolism of the shikimic acid pathway, malic acid pathway or both.
APPLICATIONS
One very good example are HORSE GRAMS- a kind
of beans
SOURCES OF PHENOLIC ACIDSHorse Grams/ beans has the following kinds of phenolic acids:
Protocatechuic acidCaffeic Acid p-coumaric acid
Thank You for Listeni
ng!
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