1. AMINO ACIDS

2. • Amino Acids are the chemical units or "building
blocks" of the body that make up proteins.
Protein substances make up the muscles,
tendons, organs, glands, nails, and hair. Growth,
repair and maintenance of all cells are
dependent upon them. Next to water, protein
makes up the greatest portion of our body
weight. Amino Acids that must be obtained from
the diet are called "Essential Amino Acids" other
Amino Acids that the body can manufacture from
other sources are called "Non-Essential Amino
Acids."

3. • Of the 20 standard proteinogenic amino acids,
10 are called essential amino acids because the
human body cannot synthesize them from other
compounds at the level needed for normal
growth, so they must be obtained from food.
However, the situation is a little more
complicated since cysteine, tyrosine, histidine
and argenine are semi-essential amino acids in
children, because the metabolic pathways that
synthesize these amino acids are not fully
developed. The amounts required also depend
on the age and health of the individual, so it is
hard to make general statements about the
dietary requirement for some amino acids.

4. Peptides
• Two individual amino acids can be linked
to form a larger molecule, with the loss of
a water molecule as a by-product of the
reaction.
• The newly created C-N bond between the
two separate amino acids is called a
peptide bond. The term 'peptide bond'
implies the existence of the peptide
group which is commonly written in text
as -CONH-

5. • Two molecules linked by a peptide bond
become what is called a dipeptide. A
chain of molecules linked by peptide
bonds is called a polypeptide
• A protein is made up of one or more
polypeptide chains, each of which consists
of amino acids which have been
mentioned earlier.

6. Peptide Bond

7. Polypeptide Bond

8. • Instead of writing out complex formulae,
sequences of amino acids are commonly
written using the previously mentioned
three- or one-letter codes eg. ala-gly-val-
leu-phe (3 letter) or AGVLF (1 letter).

9. The format of the list is: amino acid name - 3 letter code - 1 letter code
(reference to gif image, reference to interactive molecule)
• Side chain polarity Side chain
• Amino Acid 3-Letter 1-Letter acidity or basicity
• Alanine Ala A • Nonpolar neutral
• Arginine Arg R • Polar basic (strongly)
• Asparagine Asn N • Polar neutral
• Aspartic acid Asp D • Polar acidic
• Nonpolar neutral
• Cysteine Cys C
• Polar acidic
• Glutamic acid Glu E
• Polar neutral
• Glutamine Gln Q • Nonpolar neutral
• Glycine Gly G • Polar basic (weakly)
• Histidine His H • Nonpolar neutral
• Isoleucine Ile I

10. • Amino Acid 3-Letter 1-Letter Side chain polarity Side chain acidity or basicity
• Leucine Leu L nonpolar neutral
• Lysine Lys K polar basic
• Methionine Met M nonpolar neutral
• PhenylalaninePhe F nonpolar neutral
• Proline Pro P nonpolar neutral
• Serine Ser S polar neutral
• Threonine Thr T polar neutral
• Tryptophan Trp W nonpolar neutral
• Tyrosine Tyr Y polar neutral
• Valine Val V nonpolar neutral

11. • Sometimes it is not possible two
differentiate two closely related amino
acids, therefore we have the special
cases:
• asparagine/aspartic acid - asx - B
• glutamine/glutamic acid - glx - Z

12. Amino Acids in normal and zwitter
ion form

13. Here is list where amino acids are grouped according to the
characteristics of the side chains:
• Aliphatic - alanine, glycine , isoleucine, leucine,
proline, valine
• Aromatic - phenylalanine, tryptophan , tyrosine
• Acidic - aspartic acid , glutamic acid
• Basic - arginine , histidine , lysine
• Hydroxylic - serine , threonine
• Sulphur-containing - cysteine, methionine
• Amidic (containing amide group) –
asparagine, glutamine

14. Amino Acid 3- & 1- letter codes Side Chain
• alanine ala A -CH3
• arginine arg R -CH2-CH2-CH2-NH-C=NH2
NH2
• asparagine asn N -CH2-CO-NH2
• aspartic acid asp D -CH2-COO
• cysteine cys C -CH2-SH
• glutamine gln Q -CH2-CH2-CO-NH2
• glutamic acid glu E -CH2-CH2-COOH
• glycine gly G -H
• histidine his H -CH2-C = CH
+N=C-NH
H

15. • isoleucine ile I -CH-CH2-CH3
CH3
• leucine leu L -CH2-CH-CH3
CH3
• lysine lys K -CH2-CH2-CH2-NH3
• methionine met M -CH2-CH2-S-CH3
• phenylalanine phe F -CH2-Ph
• proline pro P -CH2-CH2-CH2-
(the terminus is bonded to the
main chain amine nitrogen to
form a ring)

16. • serine ser S -CH2-OH
• threonine thr T -CH-CH3
OH
• tryptophan trp W -CH2-C = CH
Ph -NH (the phenyl group is
bonded at carbons 1 and
2 ie 'ortho' positions)
• tyrosine tyr T (the phenyl group is bonded
at carbons 1 and 4 ie 'para'
positions)
• valine val V -CH2-CH3
CH3