This document discusses amino acids and their properties. It begins by explaining that amino acids are organic compounds that contain amine and carboxyl groups and have different R groups. Proteins are composed of chains of amino acids linked by peptide bonds. There are 20 standard amino acids that are the building blocks of proteins. The document then classifies amino acids based on their R groups and discusses their structures, chemical properties, and roles in the body.

1. CHARTHA. GAGLANI

2. CONTENTS
1) What are amino acids?
2) Amino acids and proteins
3) Classification of amino acids
4) Structure of amino acids
5) Physio- chemical properties
6) Chemical properties

3.  Amino acids are
organic compounds
containing amine (-
NH2) and carboxyl
(COOH) functional
groups, along with a
side chain (R group)
specific to each
amino acid.

5. Proteins are complex, organic compounds
composed of many amino acids linked together
through peptide bonds and cross-linked
between chains by , hydrogen bonds and van
der Waals forces.
 There is a greater diversity of chemical
composition in proteins than in any other group
of biologically active compounds.

6. The human body has thousands of different proteins, all
of which are necessary for staying alive and healthy.
Amino acids are the building blocks of proteins. There
are 20 different amino acids in nature. All amino acids
include five basic parts:
1)a central carbon atom
2)a hydrogen atom
3)an amino group - consisting of a nitrogen atom and
two hydrogen atoms
4)a carboxyl group - consisting of a carbon atom, two
oxygen atoms, and one hydrogen atom
5)an R-group or side chain - consisting of varying atoms

7.  Based on R- group:
1. Non-Polar amino acids
2. Polar uncharged amino acids
3. Acidic amino acids
4. Basic amino acids
 Based on diet
 Based on catabolism

8. Group I amino acids are glycine, alanine, valine, leucine,
isoleucine, proline, phenylalanine, methionine, and
tryptophan.
 The R groups of these amino acids have either aliphatic or
aromatic groups. This makes them hydrophobic (“water
fearing”).
In aqueous solutions, globular proteins will fold into a three-
dimensional shape to bury these hydrophobic side chains in
the protein interior.
1. NON POLAR AMINO ACIDS

9. ALANINE CYSTEINE
GLYCINE LEUCINE

10. 2. POLAR UNCHARGED GROUP
The polar uncharged amino acids are serine,
threonine, tyrosine, asparagine, and glutamine.
The side chains in this group possess a spectrum of
functional groups.
However, most have at least one atom (nitrogen,
oxygen, or sulfur) with electron pairs available for
hydrogen bonding to water and other molecules.

11. SERINE GLUTAMINE TYROSINE

12. The two amino acids in this group are aspartic acid and
glutamic acid.
Each has a carboxylic acid on its side chain that gives it
acidic (proton-donating) properties.
In an aqueous solution at physiological pH, all three
functional groups on these amino acids will ionize, thus giving
an overall charge of −1.
3. ACIDIC AMINO ACIDS

13. ASPARTIC ACID
GLUTAMIC ACID

14. 4. BASIC AMINO ACIDS
The three amino acids in this group are arginine,
histidine, and lysine. Each side chain is basic (i.e.,
can accept a proton).
Lysine and arginine both exist with an overall charge
of +1 at physiological pH.
The guanidino group in arginine’s side chain is the
most basic of all R groups (a fact reflected in its pKa
value of 12.5).

15. ARAGININE LYSINE
HISTIDINE

17. 1. Non-essential amino acids -An amino acid that can be
made by humans and so is not essential to the human diet.
 There are 11 nonessential amino acids: alanine, arginine,
asparagine, aspartic acid, cysteine, glutamic acid, glutamine,
glycine, proline, serine, and tyrosine.
2. Essential amino acids- Essential amino acids cannot be
cannot be made by the body but is obtained from food.
 The 9 essential amino acids are: histidine, isoleucine, leucine,
lysine, methionine, phenylalanine, threonine, tryptophan,
valine.
3. Conditionally essential- are usually not essential, except in
times of illness and stress.
 Conditional amino acids include: arginine, cysteine, glutamine,
tyrosine, glycine, ornithine, proline, serine.

18. 1. Glucogenic amino acids:
These are the amino acids that can be converted into glucose
through gluconeogenesis.
There are 13 amino acids which are glucogenic: Alanine,
Arginine, Asparagine, Aspartic acid, Cysteine, Glutamic acid,
Glutamine, Glycine, Histidine, Methionine, Proline, Serine, Valine.
2. Ketogenic amino acids:
These are the amino acids that can be degraded directly into
acetyl Co-A.
Leucine and Lysine.
3. Both glucogenic and ketogenic amino acids:
These amino acids breakdown to form both ketone bodies and
glucose.
Isoleucine, Phenylalanine, Tryptophan and tyrosine.

19. 1. Solubility:
Most of the amino acids are usually soluble in water,
and insoluble in organic solvents.
2. Melting Point:
Amino acids are generally melt at higher temperature
of above 2000C.
3. Taste:
Amino acids may be sweet (Gly, Ala & Val), tasteless
(Leu) or Bitter (Arg & Ile).

20. 4. Optical Properties:
All amino acids possess optical isomers due to the
presence of asymmetric α-carbon atoms.
5. Zwitter ion and Isoelectric point:
The name zwitter is derived from the German word which means
“hybrid”. Zwitter ion (or) dipolar ion is a hybrid molecule
containing positive & negatively ionic groups. Basically the proton
shifts from carboxyl group to amino
group of the self molecule at normal pH cellular levels.
6. Titration Curve of Glycine:
Glycine is optically inactive, simplest amino acid because which
have no asymmetric carbon atom. Acid-Base titration
involves the gradual addition (or) removal of protons. It has three
different stages when the Glycine undergoes
acid-base titration.

22. I) Due to Carboxyl group:
a) Decarboxylation:
The amino acids will undergo alpha decarboxylation to
form the corresponding “amines”. Thus important amines
are produced from amino acids.
Histidine → Histamine + CO2
Tyrosine →Tyramine + CO2

23. b) Reaction with Alkalies (Salt formation):
The carboxyl group of amino acids can release a H+ ion
with the formation of Carboxylate (COO–) ions. These
may be neutralized by cations like Na+ and Ca+2 to
form Salts. Thus amino acids react with alkalies to form
“Salts”.

24. c) Reaction with Alcohols (Esterification) :
When the amino acids is reacted with alcohol to
form, “Ester”. The esters are volatile in contrast to
the form amino acids.
Reaction with alcohols :When the amino acids is
reacted with alcohol to form, “Ester”. The esters are
volatile in contrast to the form amino acids.