Biosynthesis of different types of amino acids.pptx

Amino acids are the building blocks of proteins, playing a crucial role in various biological processes. They are categorized into essential and non-essential amino acids based on the body's ability to synthesize them. While essential amino acids must be obtained through the diet, non-essential amino acids can be synthesized by the body.

General Pathway of Amino Acid Biosynthesis:

Amino acid biosynthesis involves complex metabolic pathways that differ for each amino acid. However, a general overview can be provided:

Carbon Skeleton Formation:

Amino acids are composed of a central carbon atom (alpha carbon) bonded to a hydrogen atom, an amino group (NH2), a carboxyl group (COOH), and a side chain (R group) specific to each amino acid.
The carbon skeletons of amino acids are derived from intermediates of glycolysis, citric acid cycle, and pentose phosphate pathway.
Transamination:

A crucial step in amino acid biosynthesis is the transamination reaction, where an amino group is transferred from an amino acid donor to an alpha-keto acid acceptor.
This reaction is catalyzed by aminotransferases or transaminases, and pyridoxal phosphate (PLP) acts as a cofactor.
Specific Pathways for Essential Amino Acids:

Essential amino acids, which cannot be synthesized de novo by the body, have specific biosynthetic pathways.
For example, lysine and methionine biosynthesis involve the aspartate family pathway, while valine, leucine, and isoleucine biosynthesis occur through the branched-chain amino acid (BCAA) pathway.
Non-Essential Amino Acid Biosynthesis:

Non-essential amino acids can be synthesized by the body through various pathways.
For instance, glutamate serves as a precursor for the synthesis of several amino acids, including proline, arginine, and ornithine.
Specific Amino Acid Biosynthesis Pathways:

Serine and Glycine Biosynthesis:

Serine is derived from 3-phosphoglycerate and can be converted to glycine.
The enzyme serine hydroxymethyltransferase plays a key role in interconverting serine and glycine.
Histidine Biosynthesis:

Histidine biosynthesis involves a unique pathway that starts with phosphoribosyl pyrophosphate (PRPP) and includes several enzymatic steps.
Tyrosine and Phenylalanine Biosynthesis:

The shikimate pathway is essential for the biosynthesis of aromatic amino acids, including tyrosine and phenylalanine.
Chorismate is a key intermediate in this pathway.
Arginine Biosynthesis:

Arginine biosynthesis involves the urea cycle and the ornithine biosynthetic pathway.
Citrulline serves as a key intermediate in these processes.
Proline Biosynthesis:

Proline is derived from glutamate through a two-step reduction process involving pyrroline-5-carboxylate (P5C).
Regulation of Amino Acid Biosynthesis:

Amino acid biosynthesis is tightly regulated to maintain a balance between the body's requirements and energy conservation.
Feedback inhibition and genetic regulation play key roles in controlling the activity of enzymes involved in these p

1. Biosynthesis of Amino Acids

2. Biosynthesis of amino acids is a crucial process in living organisms, involving the production of amino acids from simple compounds. It plays a fundamental role in the overall metabolism of cells and is essential for various biological processes.

3. General Biosynthetic Pathways 1 Precursors Amino acid biosynthesis utilizes various precursors derived from central metabolic pathways, such as the citric acid cycle and glycolysis. These pathways provide the necessary building blocks for amino acid synthesis. 2 Importance The central metabolic pathways play a crucial role by supplying key intermediates required for amino acid biosynthesis, ensuring a balanced and harmonious cellular metabolism. 3 Connection A close connection between amino acid biosynthesis and central metabolic pathways ensures the integration and efficient utilization of resources within the cell.

4. Role of Enzymes in Amino Acid Biosynthesis 1 Enzyme Specificity Each step in the biosynthesis pathway involves specific enzymes that catalyze the transformation of substrates into amino acids. 2 Regulation of Enzymes Enzyme activity is tightly regulated to maintain optimal levels of different amino acids in the cell.

5. Biosynthesis of Amino Acids The carbon skeletons of many amino acids may be derived from metabolites in central pathways, allowing the biosynthesis of some, but not all, the amino acids in humans . Amino acids that can be synthesized in this way are therefore not required in the diet (nonessential amino acids)

6. The amino acids having carbon skeletons that cannot be derived from normal human metabolism must be supplied in the diet (essential amino acids ) For the biosynthesis of non-essential amino acids, amino groups must be added to the appropriate carbon skeletons This generally occurs through the transamination of an α- keto acid corresponding to that specific amino acid.

7. Amino Acid Biosynthetic families, grouped by metabolic precursors

8. Amino acids precursors are intermediates in glycolysis, the citric acid cycle, or the pentose phosphate pathway. 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 . Tryptophan , Phenyl alanine and tyrosine comes from phosphoenolepyruvate. Pyruvate used to make alanine, valine, leucine and isoleucine.

9. A spartate is formed from oxaloacetate and aspartate is used to make other amino acids like aspargine, methionine, threonine and lysine. Glutamate is synthesized from @ ketoglutarate .And from glutamate more amino acids like glutamaine, proline and arginine can be synthesised

10. Glutamate is synthesized from ammonia and  - ketoglutarate by the action of glutamate dehydrogenase. A second ammonium ion is incorporated into glutamate by the action of glutamine synthetase to form glutamine

11. Proline is a cyclized derivative of glutamate. In the first step of proline synthesis, ATP reacts with the side chain carboxyl group of glutamate to form an acyl phosphate, which is reduced by NADPH or NADH to glutamate γ- semialdehyde . This intermediate undergoes rapid spontaneous cyclization and is then reduced further to yield proline.

12. Arginine is synthesized from glutamate via ornithine and the urea cycle in animals

13. Serine, Glycine and Cysteine are derived from 3-Phosphoglycerate . The major pathway for the formation of serine is the same in all organisms In the first step, the hydroxyl group of 3-phosphoglycerate is oxidized by dehydrogenase (using NAD) to yield 3-phosphohydroxypyruvate. Transamination from glutamate yields 3- phosphoserine , which is hydrolyzed to free serine by phosphoserine phosphatase. Serine (three carbons) is the precursor of glycine (two carbons) through removal of a carbon atom by serine hydroxy methyl transferase .

14. Plants and bacteria produce the reduced sulfur required for the synthesis of cysteine (and methionine) from environmental sulfates Mammals synthesize cysteine from two amino acids: methionine furnishes the sulfur atom, and serine furnishes the carbon skeleton.

15. Biosynthesis of Aspartate

16. Aspartate Synthesis From Oxaloacetate Aspartate is synthesize by the transfer of a n ammonia group from glutamate to oxaloacetate. Aspartate can be formed in a transamination reaction. The transamination reaction is catalyzed by aspartate transaminase . This reaction uses the α - keto acid oxaloacetate as the amino acceptor and glutamate as the primary amino group donor

17. Synthesis of Asparagine from Aspartate Asparagine is synthesized from aspartate via an amidotransferase reaction catalyzed by asparagine synthetase.

18. Alanine can easily be synthesized from the alpha- keto acid pyruvate by a transamination reaction

19. 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).

20. Synthesis of valine and leucine The pathway of valine biosynthesis is a four- step pathway. Aceto lactate synthase 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 valine and leucine In the 2 nd step acetolactate is converted into 2,3- di hydroxyisovalerate in the presence of acetohydroxyacid reductoisomerase. In 3 rd step Dihydroxyacid dehydratase enzyme convert 2,3- di hydroxyisovalerate into 2- keto- isovalerate. In 4 th step 2- keto- isovalerate conevted into Valine and leucine with the help of transferase enzymes.

21. Aromatic amino acids Aromatic amino acids are amino acids that include an aromatic ring. Phenylalanine Tryptophan Tyrosine Histidine

22. Phenylalanine, tryptophan, and histidine are essential amino acids for animals. Since they are not synthesized in the human body, they must be derived from the diet . Tyrosine is semi-essential; it can be synthesized, but only from phenylalanine. A lack of the enzyme phenylalanine hydroxylase, used in tyrosine synthesis, causes phenylketonuria and concurrently renders tyrosine an essential amino acid .

23. Synthesis of the aromatic amino acids begins with the synthesis of chorismate - an important intermediate for many biosynthetic pathways . Phosphoenol pyruvate and erythrose 4-phosphate serve as beginning substrates for the pathway. A price of one NADPH + H +  and one ATP is used for every chorismate formed. In the sixth step of the synthesis another phosphoenol pyruvate molecule is added to the growing molecule Biosynthesis of Aromatic amino acids

24. Biosynthesis of Tryptophan Tryptophan synthesis is complex and involves 5 steps from chorismate . Glutamate donates an amine group in the first step of the pathway and pyruvate is lost from chorismate . In the next threes steps a ribose sugar is added, this eventually contributes to the 5 membered ring of tryptophan. Energy is contributed to the process in the form of hydrolysis of pyrophosphate. This hydrolysis helps drive the addition of the ribose sugar in the second step of the reaction. In the last step of the pathway serine serves as the donor of the  carbon amino group of tryptophan.

25. Biosynthesis of Phenylalanine and Tyrosine Phenylalanine Chorismate is converted to phenylpyruvate in two steps No energy is required to run these reactions

26. Phenylalanine is synthesized by a transamination reaction with glutamate. Tyrosine The synthesis of tyrosine is very similar to the synthesis of phenylalanine, but the reactions are carried out by different enzymes under different regulatory control.

27. Biosynthesis of Histidine The synthesis of histidine is long and complex and its pathway is intertwined with nucleic acid biosynthesis (specifically purine). The first five steps of the pathway take ribose from phosphoribosyl pyrophosphate (PRPP) and transform it into Imadiazole glycerol phosphate. Once the imadiazole ring is formed, glutamate donates the  α -amino group and the newly formed amine is oxidized to histidine in the last step of the pathway.

28. Regulation of Amino Acid Biosynthesis 1 Feedback Inhibition The end products of biosynthesis often inhibit key enzymes to prevent overproduction of amino acids. 2 Genetic Regulation Gene expression is regulated to modulate the production of enzymes involved in amino acid biosynthesis. 3 Cellular Signaling Cell signaling pathways play a role in sensing amino acid levels and adjusting biosynthesis accordingly.

29. Significance of Amino Acid Biosynthesis in Cellular Metabolism Energy Production Amino acids contribute to energy production through the citric acid cycle. Protein Synthesis Amino acids serve as the building blocks for proteins, essential for various cellular processes.