AMINO ACID & PEPTIDES

This power point contain introduction, all synthesisStrecker synthesis
(Amido-malonate
Reductive amination of alpha keto acids) (Solid phase (Merrifield)
Solution phase) of amino and and peptides.

1. BY- VISHAL SINGH SOLANKI PHARMA RISING YouTube Chennal – Pharma rising AMINO ACID & PEPTIDES PHARMA RISING

2. AMINO ACID AND PEPTIDE Amino acids  are organic compounds that contain amine (–NH 2 ) and carboxyl (–COOH) functional groups, along with a side chain (R group) specific to each amino acid . Peptides   are short chains of between two and fifty amino acids, linked by peptide bonds. PHARMA RISING

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5. AMINO ACID SYNTHESIS Strecker synthesis Amido-malonate Reductive amination of alpha keto acids PHARMA RISING

6. STRECKER SYNTHESIS The first known synthesis of an amino acid occurred in 1850 in the laboratory of Adolph Strecker in Germany. Strecker added acetaldehyde to an aqueous solution of ammonia and HCN. The product was propionitrile , which Strecker hydrolyzed to racemic alanine . PHARMA RISING

7. MECHANISM PHARMA RISING

8. CONTI… In a separate step, hydrolysis of the nitrile gives an a-amino acid PHARMA RISING

9. AMIDO-MALONATE/ GABRIEL-MALONIC ESTER SYNTHESIS The conventional malonic ester synthesis involves alkylation of diethyl malonate , followed by hydrolysis and decarboxylation to give an alkylated acetic acid. PHARMA RISING

10. REDUCTIVE AMINATION OF ALPHA KETO ACIDS When an alpha keto acid is treated with ammonia, the ketone reacts to form an imine . The imine is reduced to an amine by hydrogen and a palladium catalyst. Under these conditions, the carboxylic acid is not reduced. The product is a racemic acid.

11. CONTI… The following reaction shows the synthesis of racemic phenylalanine from 3 phenyl-2-oxopropanoic acid. PHARMA RISING

12. CO-VALENT BONDING IN PEPTIDES A  peptide bond  is an amide type of covalent chemical bond linking two consecutive alpha-amino acids from C1 (carbon number one) of one alpha-amino acid and N2 (nitrogen number two) of another, along a peptide or protein chain. PHARMA RISING

13. EXAMPLE OF PEPTIDE BOND PHARMA RISING

14. SYNTHESIS OF PEPTIDES Solid phase (Merrifield ) Solution phase PHARMA RISING

15. 1. SOLID PHASE (MERRIFIELD) In chemistry solid-phase synthesis is a method in which molecules are bound on a bead and synthesized step-by-step in a reactant solution; compared [with] normal synthesis in a liquid state, it is easier to remove excess reactant or by-product from the product. This method is used for the synthesis of peptides, deoxyribonucleic acid (DNA), and other molecules that need to be synthesized in a certain alignment. This method has also been used in drug discovery process PHARMA RISING

16. PROBLEMS WITH TRADITIONAL SYNTHESIS 1 chemist 1 molecule Can only make one molecule at a time. Each synthesis very time consuming. Purification of products very time-consuming between steps. Yields can be low and produces very few molecules at a time for testing.

17. PRINCIPLE OF SOLID PHASE SYNTHESIS

18. ESSENTIAL REQUIREMENTS a cross-linked insoluble polymeric support which is inert to the synthetic conditions (e.g. a resin bead) an anchor or linker covalently linked to the resin—the anchor has a reactive functional group that can be used to attach a substrate a bond linking the substrate to the linker, which will be stable to the reaction conditions used in the synthesis a means of cleaving the product or the intermediates from the linker protecting groups for functional groups not involved in the synthetic route. PHARMA RISING

19. PLANNING OF SOLID PHASE SYNTHESIS The Resin (Solid Support) The Linkers The Protective groups PHARMA RISING

20. THE SOLID SUPPORT The resin involved consisted of polystyrene beads where the styrene is partially cross-linked with 1% divinylbenzene . The beads are derivatized with a chloromethyl group (the anchor/ linker) to which amino acids can be coupled via an ester group. This ester group is stable to the reaction conditions used in peptide synthesis, but can be cleaved at the end of the synthesis using vigorous acidic conditions (hydrofluoric acid). PHARMA RISING

21. EXAMPLE OF BEAD polystyrene beads where the styrene is partially cross-linked with 1% divinyl -benzene. Sheppard's polyamide resin Tentagel resin is 80% polyethylene glycol grafted to cross-linked polystyrene, and provides an environment similar to ether or tetra-hydro-furan. PHARMA RISING

22. PEPTIDE SYNTHESIS ON A SOLID SUPPORT ( Boc = tert - butyloxy -carbonyl (t - BuO -CO); TFA = trifluoro -acetic acid).

23. PEPTIDE SYNTHESIS WITH A WANG RESIN

24. THE ANCHOR/LINKER The anchor/linker is a molecular unit covalently attached to the polymer chain making up the solid support. It contains a reactive functional group with which the starting material in the proposed synthesis can react and hence become attached to the resin. PHARMA RISING

25. CONTI… The resulting link must be stable to the reaction conditions used throughout the synthesis, but be easily cleaved to release the final compound once the synthesis is complete. Different linkers are used depending on: the functional group which will be present on the starting material the functional group which is desired on the final product once it is released. For example Wang resin - suitable for the attachment and release of carboxylic acids. Rink resin - Starting materials with a carboxylic acid (RCO 2 H) can be linked to the Rink resin via an amide link. PHARMA RISING

26. CONTI… PHARMA RISING

27. PROTECTING GROUPS  A  protecting group  or  protective group  is introduced into a molecule by chemical modification of a functional group to obtain chemo-selectivity in a subsequent chemical reaction.  protecting groups is essential during peptide synthesis to avoid undesirable side reactions, such as self-coupling of the activated amino acid leading to (polymerization). Two main example of protecting group; Boc / Bzl - The Boc / Bzl strategy utilizes TFA-labile N-terminal  Boc  protection alongside side chain protection that is removed using anhydrous hydrogen fluoride during the final cleavage step. Fmoc / t Bu - Fmoc / tBu SPPS uses base-labile  Fmoc  N-terminal protection, with side chain protection and a resin linkage that are acid-labile. PHARMA RISING

28. Eg . OF SOLID-PHASE PEPTIDE SYNTHESIS The first step is attachment of the N-protected C-terminal amino acid ( Boc -phenylalanine) to the polymer

29. CONTI… Trifluoroacetic acid (TFA) cleaves the Boc protecting group of phenylalanine so that its amino group can be coupled with the next amino acid. PHARMA RISING

30. CONTI… The second amino acid ( valine ) is added in its N-protected Boc form so that it cannot couple with itself. Addition of DCC couples the valine carboxyl group with the free group of phenylalanine. DCC – N,N Dicyclohexylcarbodiimide PHARMA RISING

31. CONTI… To couple the final amino acid ( alanine ), the chain is first deprotected by treatment with trifluoroacetic acid. Then the N-protected Boc-alanine and DCC are added. PHARMA RISING

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33. CONTI… If we were making a longer peptide, the addition of each subsequent amino acid would require the repetition of two steps: Use trifluoroacetic acid to deprotect the amino group at the end of the growing chain. Add the next Boc -amino acid, using DCC as a coupling agent. Once the peptide is completed, the final Boc protecting group must be removed, and the peptide must be cleaved from the polymer. Anhydrous HF cleaves the ester linkage that bonds the peptide to the polymer, and it also removes the Boc protecting group. PHARMA RISING

34. CONTI… Remember that solid-phase peptide synthesis: Goes Attach the Boc -protected C terminus to the bead first. Couple each amino acid by removing (TFA) the Boc group from the N terminus, then add the next Boc protected amino acid with DCC. Cleave (HF) the finished peptide from the bead PHARMA RISING

35. 2. SOLUTION PHASE SYNTHESIS Solution-phase peptide synthesis begins at the N terminus and ends at the C terminus, or left to right as we draw the peptide. The first major step is to couple the carboxyl group of alanine to the amino group of valine . This cannot be done simply by activating the carboxyl group of alanine and adding valine . If we activated the carboxyl group of alanine , it would react with another molecule of alanine PHARMA RISING

36. CONTI… To prevent side reactions, the amino group of alanine must be protected to make it nonnucleophilic . It is called the benzyloxycarbonyl group , the carbobenzoxy group ( Cbz ), or simply the Z group (abbreviated Z). Preliminary step: Protect the amino group with Z. PHARMA RISING

37. CONTI… Step 1: Activate the carboxyl group with ethyl chloroformate . Step 2: Form an amide bond to couple the next amino acid. PHARMA RISING

38. CONTI… Step 3: Activate the carboxyl group with ethyl chloroformate . Step 4: Form an amide bond to couple the next amino acid. PHARMA RISING

39. CONTI… To make a larger peptide, repeat these two steps for the addition of each amino acid residue: Activate the C terminus of the growing peptide by reaction with ethyl chloroformate . Couple the next amino acid. Step 5: Remove the protecting group. PHARMA RISING

40. SOLID PHASE SOLUTION PHASE WRITE THE D/F B/W PEPTIDE SYNTHESIS

41. REFERENCE GRHAM L. PETRIC/MEDICINAL CHEMISTRY/ BOOK WADE/ AMINO ACID, PEPTIDE AND PROTEIN/ BOOK WIKIPEDIA.COM SLIDESHARE.NET GOOGLE.COM PHARMA RISING

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