Amino acid ( Introduction, classification, structure, properties, qualitative test and disease associated with amino acid)

An amino acid is an organic molecule that is made up of a basic amino group (−NH2), an acidic carboxyl group (−COOH), and an organic R group (or side chain) that is unique to each amino acid. The term amino acid is short for α-amino [alpha-amino] carboxylic acid.

1. Mohd Asad Farooqi (Lecturer) Mahrishi college of pharmacy 1/7/2021 1

2. C O N T E N TS INTRODUCTION HISTORY CLASSIFICATION STRUCTURE PROPERTIES CONCLUSION REFERENCES 1/7/2021 2

3. INTRODUCTION Amino acids are a group of organic compounds containing two functional groups-amino and carboxyl . The amino group (-NH) is basic while the carboxyl group – (-COOH) is acidic in nature. General structure of amino acids The amino acids are termed as α-amino acids, if both the carboxyl and amino groups are attached to the same carbon atom. The α-carbon atom binds to a side chain represented by R which is different for each of the 20 amino acids found in proteins. The amino acids mostly exist in the ionized form in the biological system. H H R -C- COOH R -C- COO - NH 2 NH + 3 1/7/2021 3

4. CLASSIFICATION OF AMINO ACID 1/7/2021 4

5. Nutritional classification of amino acid Essential or indispensable amino acid Non-essential or dispensable amino acid 1/7/2021 5

6. 1. ESSENTIAL AMINO ACIDS The amino acid which cannot be synthesized by the body and, therefore need to be supplied through the diet is called essential amino acids. Ten amino acids comes under this group. Arginine ,Valine , Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan 1/7/2021 6

7. 2. NON ESSENTIAL AMINO ACIDS The body can synthesize about 10 essential amino acids to meet the biological needs hence they need not be consumed in the diet. Glycine, Alanine, Serine, Cysteine, Aspartate, Asparagine, Glutamate, Glutamine, Tyrosine, and Proline. 1/7/2021 7

8. Sl n o. Name symbol Structure 3 letters 1 letter I. AMINO ACIDS WITH ALIPHATIC SIDE CHAIN 1. Glycine Gly G -CH-COO - NH + 3 2. Alanine Ala A CH 3 -CH-COO - NH + 3 3. Valine Val V H 3 C CH H 3 C -C H - C O O - NH + 3 1/7/2021 8

9. 4. L e u c i ne L e u L 5. Isoleucine I le I II. AMINO ACID CONTAINING HYDROXYL (-OH) GROUP 6. S e r i n e S e r S 7. Threonine T h r T -CH-COO - NH + 3 -CH-COO - NH + 3 H 3 C CH-CH 2 H 3 C CH 3 CH 2 CH H 3 C -CH-COO - NH + 3 -CH-COO - NH + 3 20 1/7/2021 9

10. III. SULFUR CONTAINING AMINO ACIDS 8. Cysteine Cys C -CH-COO - NH + 3 9. Methionine Met M -CH-COO - NH + 3 IV. ACIDIC AMIO ACIDS AND THEIR AMIDES 10. Aspartic acid Asp D -CH-COO - NH + 3 11. Asparagine Asn N -CH-COO - NH + 3 1/7/2021 10

11. 12. Glutamic acid G lu E -CH-COO - NH + 3 13. Glutamine G ln Q - C H - C O O - NH + 3 v. Basic amino acids 14. Lysine L y s K -CH-COO - NH + 3 15. Arginine A r g R NH-CH 2 -CH 2 -CH 2 C=NH + 2 -CH-COO - NH + NH 2 3 1/7/2021 11

12. 16. Histidine His H -CH-COO - NH + 3 VI. AROMATIC AMINO ACIDS 17. Phenylalanine Phe F -CH-COO - NH + 3 18. Tyrosine Tyr Y - C H - C OO - NH + 3 19. Tryptophan Trp W -CH-COO - NH + 3 1/7/2021 12

13. VI. Imino acid 20. Proline Pro P N C OO - H 1/7/2021 13

14. PROPERTIES OF AMINO ACIDS The amino acids differ in their physiochemical properties which determine the characteristic of protein. Physical properties Chemical properties 1/7/2021 14

15. A. PHYSICAL PROPERTIES Solubility : Most of the amino acids are usually soluble in water and insoluble in organic solvents. Melting point : Amino acids generally melt at higher temperatures, often above 200°C. Taste : Amino acids may be sweet (Gly, Ala, Val), tasteless (Leu) or bitter (Arg, Ile), Monosodium glutamate (MSG; ajinomotto) is used as a flavouring agent in food industry. 1/7/2021 15

16. 4. Amino acids as ampholytes : amino acid contains both acidic(-COOH) and basic (-NH 2 ) groups. They can donate a proton or accept a proton , hence amino acids are regarded as ampholytes. 1/7/2021 16

17. CONT……… 6. Zwitterion or dipolar ion : it is a hybrid molecule containing positive and negative groups. The amino acids rarely exist in a neutral form with free carboxylic (-COOH) and free amino (-NH) groups. In strongly acidic pH(low pH), the amino acid is positively charged (cation) while in strongly alkaline pH (high pH), it is negatively charged (anion). Each amino acid has a characteristic pH (e.g. leucine, pH 6.0) at which it carries both positive and negative charge and exist as a zwitter ion. 1/7/2021 17

18. B. CHEMICAL PROPERTIES Reaction with ammonia : The carboxyl group of dicarboxylic amino acids reacts with NH 3 to form amide Aspartic acid + NH + 3 ------> Aspargine Glutamic acid + NH + 3 -----> Glutamine The amino acid behave as bases and combines with acids (e.g. HCL) to form salts (- NH + Cl - ). 3 1/7/2021 18

19. COLOUR REACTION OF AMINO ACIDS SL. NO. REACTION SPECIFIC GROUP OR AMINO ACID COLOUR 1. Xanthoproteic reaction Benzene ring of aromatic amino acids (Phe, Try, Trp) Yellow 2. Millons reaction Phenolic group (Tyr) Red 3. Hopkins-Cole reaction Indole ring (Trp) Purple 4. Sakaguchi reaction Gaunidino group (Arg) Red 5. Nitroprusside reaction Sulfhydryl group (Cys) Bright red 6. Pauly’s test Imidazole ring (His) Red 1/7/2021 19

20. Polypeptides and Proteins In 1902, Emil Fischer proposed that proteins are long chains of amino acids joined by peptide bonds Peptide bond: the special name given to the amide bond between the  - carboxyl group of one amino acid and the  -amino group of another 1/7/2021 20

21. Pep t i d es ▫ Peptide: The name given to a short polymer of amino acids joined by peptide bonds; they are classified by the number of amino acids in the chain ▫ Dipeptide: A molecule containing two amino acids joined by a peptide bond ▫ Tripeptide: A molecule containing three amino acids joined by peptide bonds ▫ Polypeptide: A macromolecule containing many amino acids joined by peptide bonds ▫ Protein: A biological macromolecule of molecular weight 5000 g/mol or greater, consisting of one or more polypeptide chains 1/7/2021 21

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28. CONCLUSION Amino acids are at the basis of all life processes, as they are absolutely essential for every metabolic process. Among their most important tasks are the optimal transport and optimal storage of all nutrients (i.e., Water, fat, carbohydrates, proteins, minerals and vitamins). The majority of diseases such as obesity, high- cholesterol levels, diabetes, insomnia, erectile dysfunction or arthritis can essentially be traced back to metabolic disturbances. This also applies to hair loss and serious cases of wrinkle formation. The positive effects of amino acids on: Arthritis, Osteoporosis, Cholesterol, Diabetes, Fat-burning, Healthy skin, Hair loss, Sleep, Mind swings and Performance. 1/7/2021 28

29. REFERENCES -DAVID L. NELSON AND MICHAEL M. COX, THIRD EDITION, LEHNINGER, PRINCIPLES OF BIOCHEMISTRY - U. SATYANARAYANA AND U. CHAKRAPANI, THIRD EDITION, BIOCHEMISTRY 1/7/2021 29

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