Amino acids are organic compounds that combine to form proteins. They contain amine and carboxyl groups and are made up of carbon, hydrogen, oxygen, and nitrogen. The 20 standard amino acids are the building blocks of proteins. Essential amino acids cannot be produced by the body and must be obtained through food, while nonessential amino acids can be produced by the body. Amino acids exist as zwitterions at physiological pH and are important for building muscle, producing hormones, and many other bodily functions.

1. AMINO ACIDS
Building blocks of protein
Mrs. Praveen Garg
VITS College, Satna

2. INTRODUCTION
 Amino acids are organic compounds that combine to form
proteins.
 Amino acids and proteins are the building blocks of life.
 When proteins are digested or broken down, amino acids are
left.
 Amino acids contain amine and carboxyl functional groups,
along with a side chain specific to each amino acid.
 The key elements of an amino acid are carbon, hydrogen,
oxygen, and nitrogen, although other elements are found in
the side chains of certain amino acids.
 Amino acids can also be used as a source of energy by the
body.

3.  The human body uses amino acids to make proteins to help the
body.
• Break down food
• Grow
• Repair body tissue
• Perform many other body functions

4. • Arginine - Arg – R
• Lysine - Lys – K
• Aspartic acid - Asp – D
• Glutamic acid - Glu – E
• Glutamine - Gln – Q
• Asparagine - Asn – N
• Histidine - His – H
• Serine - Ser – S
• Threonine - Thr – T
• Cysteine - Cys - C
• Tryptophan - Trp – W
• Tyrosine - Tyr – Y
• Methionine - Met – M
• Alanine - Ala – A
• Isoleucine - Ile – I
• Leucine - Leu – L
• Phenylalanine - Phe – F
• Valine - Val – V
• Proline - Pro – P
• Glycine - Gly - G
TYPES OF AMINO ACIDS
The 20 most common amino acids in proteins are listed with their three
letter and one-letter codes:

5. ESSENTIAL AMINO ACIDS
• Essential amino acids
cannot be made by the body.
As a result, they must come
from food.
Example:
• Histidine, isoleucine,
leucine, lysine, methionine,
phenylalanine,
threonine, tryptophan, and
valine.
NONESSENTIAL AMINO ACIDS
• Nonessential means that
our bodies produce an
amino acid, even if we do
not get it from the food we
eat.
Example:
• Alanine, arginine,
asparagine, aspartic acid,
cysteine, glutamic acid,
glutamine, glycine, proline,
serine, and tyrosine.
CLASSIFICATION
Amino acids are classified into two groups:

6.  They can be classified according to the core structural functional
groups' locations as alpha-(α-), beta-(β-), gamma-(γ-) or delta-(δ-
) amino acids.
 Other categories relate to polarity, pH level, and side chain group
type (aliphatic, acyclic, aromatic, containing hydroxyl or sulfur,
etc.).

7. Classification Based on Polarity
Non polar amino acids:
• They have equal number
of amino and carboxilic
group.
• These are hydrophobic
and no charge on the R
group.
• Example: alanine, valine,
leucine, isoleucine,
phenyl alanine, glycine,
tryptophen, methionine
and proline.

8. Polar amino acid with no charge:
• They do not have any charge on R group.
• They help in participate in hydrogen bonding of protein structure.
• Example: serine, threonine, tyrosine, cysteine, glutamine,
aspargine.

9. Polar amino acid with positive charge:
• They have more amino groups as compared to carboxyl groups
making it basic.
• Example: Lysine, Arginine, Histidine

10. Polar amino acid with negative charge:
• They have more carboxilic group than amino group making
them acidic.
• Example: Aspartic acid, Glutamic acid

11.  Acidic amino acids: These contain one amino and two
carboxilc group.
Example: Aspartic acid, glutamic acid
 Basic amino acids: These contain an additional basic
such as amino group, guanidine, imidazole.
Example: Lysine, Arginine, Histidine
 Neutral amino acids: These contain one amino and one
carboxilic group.
Example: Glycine, Alanine, etc.
Classification Based on Acid/Base

12. ZWITTER ION
• A zwitterion, also called an inner salt, is a molecule that contains
an equal number of positively and negatively charged functional
groups.
• The example of zwitter ion is amino acid that contain -COOH
and –NH2 group in same molecule.
• In aqueous solution, -COOH group loses a proton (H+) to form a
carboxylate (-COO-) ion while –NH2 group gains a proton to
form –NH3 ion, thus they exist as a dipolar ion at pH 7. Such a
ion is called zwitter ion.

13. Acidic solution Neutral solution
Zwitter ion
Alkaline solution
• Amino acids are amphoteric molecule, they can donate or
accept protons and act like as acidic and basic.

14. PROPERTY OF AMINO ACIDS
Physical Properties:
• Amino acids are colorless, crystalline solid.
• They are soluble in water, slightly soluble in alcohol and
dissolve with difficulty in methanol, ethanol, and propanol.
• R-group of amino acids and pH of the solvent play important
role in solubility.
• All amino acids have a high melting point greater than 200o
• All amino acids (except glycine) are optically active.
• Amino acids can connect with a peptide bond involving their
amino and carboxylate groups.
• A covalent bond formed between the alpha-amino group of
one amino acid and an alpha-carboxyl group of other forming
-CO-NH-linkage.

15. Chemical property
1. Decarboxylation: In this process, amino acids produce
amines.
Example: Histidine Histamine + CO2
Tyrosine Tyramine + CO2
Glutamic acid Gamma aminobutyric acid + CO2
Tryptophen Tryptamine + CO2
,
Due to –COOH group

16. 2. Reaction with ammonia: The carboxyl group of
dicarboxilic amino acids react with NH3 to form amide.
• Aspartic acids + NH3 Asparagine
• Glutamic acids + NH3 Glutamine
3. Salt formation: Amino acids form salts (-COONa) with bases
and form esters (-COOR) with alcohols.

17.  Due to – NH2 group
1. Reaction with Sanger reagent: 1-Fluoro-2,4-dinitrobenzene
(commonly called Sanger's reagent, dinitrofluorobenzene, DNFB
or FDNB) is a chemical that reacts with the N-terminal amino
acid of polypeptides and produce yellow color derivatives 2,4
dinitrobenzene (DNB).

18. 2. Edmann reaction:
An uncharged peptide is reacted with phenylisothiocyanate
(PITC) at the amino terminus under mildly alkaline conditions
to give a phenylthiocarbamoyl derivative (PTC-peptide).

19. 3. Nin hydrin reaction:
• Ninhydrin reacts with the α-amino group of primary amino
acids producing 'Ruhemann's purple'. The chromophore formed is
the same for all primary amino acids.

20. Functions of Amino acids
• In particular, 20 amino acids are crucial for life as they form
peptides and proteins and are known to be the building blocks
for all living things.
• The linear sequence of amino acid residues in a polypeptide
chain determines the 3D- configuration of a protein, and the
structure of a protein determines its function.
• Amino acids are essential for the health of the human body.
 They largely promote the production of hormone.
 Structure of muscles
 Human nervous system’s healthy functioning
 The health of vital organs.
 Normal cellular structure

21. • The amino acids are used by various tissues to synthesize
proteins and to produce nitrogen-containing compounds (e.g.,
purines, heme, creatine, epinephrine), or they are oxidized to
produce energy.
THANK YOU