Amino acids abhishek sharma

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Amino acids abhishek sharma

  1. 1. AMINO ACIDS Abhishek Sharma B.Pharmacy 5th sem Shoolini university
  2. 2. Amino acids • Amino acids are building blocks of proteins. Proteins are composed of 20 different amino acid. • Amino acids are organic compounds having an amino group attached to a chain containing an acid group. Amino acid derived from proteins have the amino group on a-carbon that is the carbon atom next to the carboxyl group. • R group may be hydrogen, aliphatic group, or aromatic ring.
  3. 3. CLASSIFICATION (ON THE BASIS OF STRUCTURE)  Amino acids are classified as neutral, acidic, or basic according to no of amino acids and carboxyl group in the molecule.  1) Neutral amino acids - contain one amino acid and one carboxyl group R C COOH  NH2 2) Acidic amino acids - contain one amino group and two carboxyl group HOOC CH NH2 COOH
  4. 4. 3) Basic amino acids – contain two amino groups and one carboxyl group. H2N CH NH2 COOH
  5. 5. CLASSIFICATION – ON THE BASIS OF POLARITY 1) Non polar amino acids – the are also referred to as hydrophobic (water hating) They have no charge on R group. Glycine (Gly) Methionine (Met) Alanine (Ala) Phenylalanine (Phe) Valine (Val) Tryptophan (Trp) Leucine (leu) Isoleucine (Ile)
  6. 6. 2) POLAR AMINO ACIDS WITH NO CHARGE ON R GROUP They carry no charge on R group. They possess groups such as hydroxyl, sulfhydril and amide. Serine (Ser) Threonine (Thr) Tyrosine (Tyr) Cysteine (cys) Asparagine (Asn) Glutamine (Gln)
  7. 7. 3) POLAR AMINO ACID WITH POSITIVE R GROUP  Lysine (Lys) Arginine (Arg) Histidine (His) 4) Polar amino acid with negative R group Aspartic acid (Asp) Glutamic acid (Glu)
  8. 8. CLASSIFICATION ON THE BASIS OF NUTRTION  Eesential amino acids – cannot be synthesized by the body. Therefore they must be present in our diet. Arginine* Histidine* Isoleucine Leucine Valine Lysine Methionine Threonine Phenylalanine Tryptophan * Can be synthesized by adults but not by growing children. They are also called as semi essential amino acids.
  9. 9.  Non essential amino acids – They are synthesized in our body. Hence they need not to be consumed in the diet. Alanine Asparagine Aspartate Glutamate Glutamine Glycine Proline Serine Cysteine Tyrosine
  10. 10. CLASSIFICATION ON THE BASIS OF METABOLIC FATE  1) Glycogenic amino acid – these amino acids serve as a precursor for the formation of glucose or glycogen. eg. alanine, aspartate, glycine, methionine etc. 2) Ketogenic amino acid – fat can be synthesized from these amino acids. eg. Lucine and lysine
  11. 11. PROPERTIES OF AMINO ACIDS  Solubility: most of the amino acids are soluble in water and insoluble in organic solvents.  Melting point: melt at higher temperature (above 200 c)  Taste: sweet - glycine, alanine, valine tasteless – leucine bitter – arginine, isoleucine  Optical activity: all the amino acids except glycine possess optical isomers due to presence of asymmetric carbon atom. glycine 
  12. 12.  Alanine and all other amino acids have an asymmetric carbon at position 2 (the a-carbon atom). For this reason they all are optically active and exist in D and L forms. Which are non super-imposable mirror images.
  13. 13. Amino acids as ampholytes : amino acids contain both acidic (-COOH) and basic (-NH2) groups. They can donate a proton and accept a proton. Hence they are also called as ampholytes.  Zwitter ions : Amino acids also exist in zwitter ion form. zwitter ion is a hybrid molecule that contain both positive as well as negative ionic groups. eg. leucine - at isoelectric ph - carries no net charge 
  14. 14. CHEMICAL PROPERTIES  A) Reactions due to carboxylic group 1)amino acids form salts (-COONa) with bases and estres (-COOR) with alcohols. 2) Deacarboxylation : amino acids undergo decarboxylation to produce amines. H2N-CH2-COOH + Ba(OH)2 glycine CH3-NH2 + BaCO3 + H2O methylamine 3) Reaction with ammonia : form amides aspartic acid + NH3 glutamic acid + NH3 aspargamine glutamine
  15. 15. REACTIONS DUE TO NH2 GROUP 1 ) Amino groups behave as bases and combine with acids (eg.HCl) to form salts. 2) Reaction with ninhydrin the a-amino acid react with ninhydrin to form a purple, blue or pink colour complex. Ninhydrin reaction is used for the quantitative determination of amino acids and proteins.
  16. 16.  Oxidative deamination :The amino acids undergo oxidative deamination to liberate free ammonia.  Transmethylation: transfer of amino group from an amino acid to a keto group is called transmethylation
  17. 17. REFERENCE: Biochemistry – u. satyanarayana  Advanced organic chemistry – bahl n bahl  Thank you

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