This slide show is about overview of building blocks of life i.e. amino acids. It is describes physical, chemical properties, classification, biological functions, modified products of amino acids and biosynthesis of amino acids.

1. Amino Acids
Dr. Anil V Dusane
Sir Parashurambhau College
Pune, India
anildusane@gmail.com
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2. Introduction
• Amino acids are the monomers of proteins.
• These are building blocks of proteins.
• Proteins of the plant, animal and microbes and synthesized from
20 amino acids.
• Amino acids are derivatives of carboxylic acids in which a
hydrogen atom in a -carbon chain is replaced by an amino
group (-NH2).
• In -amino acids, an amino and a carboxyl
group attached to the same () carbon atom.
R represents a great variety of structures.
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3. Physical Properties of Amino acids
1. Nature:  amino acids are colorless, crystalline, solid and stable.
2. Solubility: Amino acids are soluble in polar solvents such as
ethanol, insoluble in non-polar solvents such as benzene and ether
and most of the amino acids are sparingly soluble in water.
3. Melting point: Amino acids have high melting point (>200oC). On
heating to high temperatures these decomposes.
4. Optical activity: All amino acids (except glycine) are optically
active.
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4. Chemical Properties of Amino acids
1. Formation of peptide bond: It is a covalent bond formed between
the alpha-amino group of one amino acid and an alpha-carboxyl
group of other forming -CO-NH-linkage.
2. Characteristic caroboxylate ion: Amino acids shows absorption
bands near 1400 and 1600 cm-1.
3. Formation of complex: Amino acids forms purple, blue or pink colour
complex with ninhydrin.
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5. Chemical Properties of Amino acids
4. Amphoteric nature: Amino acids act as both acids and base
since due to the two amine and carboxylic group present.
(Acid<----------> Base)
5. Zwitterions: Amino acids are the best-known examples of
zwitterions. A zwitterion is a molecule with functional
groups, of which at least one has a positive and one has a
negative electrical charge.
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6. Classification of amino acids
Based on polarity, charge and group
• Nonpolar, Aliphatic amino acids: R groups in this class of amino acids
are nonpolar and hydrophobic. E.g. Glycine and Alanine
• Polar, Uncharged amino acids: R groups of these amino acids are
more soluble in water, or more hydrophilic, than those of the nonpolar
amino acids. E.g. Serine and cysteine.
• Aromatic amino acids: Amino acids are with aromatic side chains.
These are relatively nonpolar (hydrophobic). E.g. Phenylalanine,
tyrosine, and tryptophan.
• Acidic amino acids: In this amino acids R-group is acidic or negatively
charged. E.g. Glutamic acid and Aspartic acid
• Basic amino acids: In this amino acids R-group is basic or positively
charged. E.g. Lysine and Arginine.
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7. Functions of amino acids
1. Protein synthesis: Twenty amino acids (with specified by genetic code) are essential
for protein synthesis in organisms.
2. Formations of purines and pyrimidine for synthesis of DNA: Asparagine is
mainly involved in the transportation of nitrogen.
3. Reservoir of nitrogen: Adequate amount of amino acids are required to maintain
proper nitrogen balance.
4. Essential part of human diet: Diet must contain essential amino acids (which are
not synthesized in body) e.g. Valine, arginine, leucine, isolucine, threonine,
methonine, phenyl-alanine, tryptophan, histidine, and lysine.
5. Healthy nervous system: Phenylalanine helps in maintaining a healthy nervous
system and in boosting the memory power. Glutamic acid acts as a neurotransmitter
and is mainly involved in the development and functioning of a human brain.
Asparagine is mainly involved in the development of the nervous system and in
improving our body stamina.
6. Immune system: Threonine helps in promoting the functions of the immune system.
Lysine is necessary for promoting the formation of antibodies
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8. Functions of amino acids
7. Improved blood flow and reduced blood pressure: Glutamic acid participates in the
formation of citrulline (L-citrulline is a naturally occurring amino acid found in
watermelon. It might open up veins and arteries to improve blood flow and reduce blood
pressure). Threonine helps in promoting the functions of the immune system.
8. Muscle growth: Valine and Serine acts as an important component in promoting the
muscle growth.
9. Preventing arteriosclerosis: Proline is involved in preventing the thickening and
hardening of the walls of the arteries (arteriosclerosis).
10. Healing of wounds: Glycine is helpful in healing of wounds.
11. Detoxification: Arginine helps in detoxification of the kidneys.
12. Production of B complex: Tryptophan is involved in the production of vitamin B3
13. Formation of haemoglobin and insulin: Isoleucine plays a vital role in the formation
of haemoglobin, stimulating the pancreas to synthesize insulin.
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9. Modified products of Amino acids
1. Thyroxine: It replaces or provides more thyroid hormone, which
is normally produced by thyroid gland. It is formed from tyrosine.
2. -alanine: It improves athletic performance and exercise
capacity, building lean muscle mass, and improving physical
functioning in the elderly. It is a component of coenzyme A and
vitamin pantothenic acid.
3. Gamma Aminobutyric Acid (GABA): It is formed in brain by
decarboxylation of glutamic acid. It is an inhibitory transmitter in
Central Nervous System (CNS). It reduces excitability of nervous
system.
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10. 4. Histidine: Decarboxylation product of histidine involved in
shock and allergic reactions. Histidine act as vasodilator. It is
involved in many enzymatic processes and in the synthesizing
of both red blood cells and white blood cells.
5. Serotonin: It is synthesized from tryptophan): has role in
transmission of nerve impulses. It is powerful vasoconstrictor
and stimulates construction of smooth muscle It occurs in
brain, gut and blood plates. This serotonin hormone plays a
vital role in maintaining our appetite, regulate sleep and
boosts our moods.
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11. Biosynthesis of Amino acids
• Amino acid synthesis is the set of biochemical
processes (metabolic pathways) by synthesis of
amino acids take place.
• Most important step in the metabolism
• This takes place by two important methods i.e.
Reductive amination and Transamination
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12. Overview of amino acid metabolism
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13. Reductive amination
• In this process, ketoacid after reacting with ammonia get
converted into amino acid.
• Reduction of organic acids takes place in the presence of
dehydrogenase enzyme and NADH2.
• Amino acids are synthesized in the following two steps.
• 1. Ketoacid reacts with NH3 and forms iminoacids.
• 2. Iminoacid is converted into glutamic acid in the presence of
NADH2 and dehydrogenase.
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14. Reductive amination
-ketogluramic acid + NH3 = iminoglutamic acid=(dehydrogenase and NADH2) Glutamic acid+ NAD.
• It is thought that only glutamic acid is formed as primary amino
acid by direct amination of ketoacid.
• Production of glutamic acid is the most important step in
nitrogen assimilation because 70%-80% N2 is assimilated by
above process.
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15. Transamination
• Once the primary amino acid (glutamic acid) is formed then
from this different amino acids are synthesized
• Process involves transfer of amino group from one amino acid
to carboxyl group of ketoacid.
• Enzymes like transaminase or aminotransferases catalyze this
transamination process.
• Different enzymes viz. aspartate transaminase, alanine
transaminase, leucine transaminase, etc. are involved in
transamination.
• Transamination involves participation of PLP (Pyridoxal 5-
phosphate) that is a derivative of pyridoxin. 15

16. Transamination
Glutamic acid + Oxalo acetic acid =(aspertate transaminase)-ketoglutaric acid+ aspartic acid
(Donar amino acid) (acceptor ketoacid) (product ketoacid) (product amino acid)
• Different types of amino acids can be formed by above method.
• e.g. Glutamic acid + pyruvic acid = (alanine transferases ) Oxalo acetic acid +
alanine.
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17. Questions
Q1. What are amino acids? Explain their significance.
Q2. Write an account on biosynthesis of amino acids.
Q3. Write about classification of amino acids.
Q4. Write short notes on
i) Reductive amination
ii) Transamination
iii) Properties of amino acids
iv) Functions of amino acids
v) Classification of amino acids.
vi) Modified products of amnio acids.
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18. Thanks
Dr. Anil V Dusane
S.P. College, Pune, India
anildusane@gmail.com
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