AMINO ACID METABOLISM

1. COMPOSITION &
METABOLISM OF AMINO
ACIDS / PROTEINS
UNIT – V
By: Mr. Sathish Rajamani M. Sc (N)

2. INTRODUCTION
• Protein – Greek word ‘Protos’ which means ‘
OF FIRST IMPORTANCE’.
• Proteins represents a group of complex
nitrogenous compounds, having high
molecular weight.

3. OCCURRENCE &
FUNCTIONS
• Found in all living cells.
• They are essential constituents of
protoplasm & cell membrane.
• Proteins are presents in genes as nucleo –
proteins.
• They also form components of catalysts
called enzymes.

4. • Proteins form about 15 % of the total
body weight of an adult.
• All proteins contains carbon,
hydrogen, oxygen and nitrogen. Some
proteins also contains sulphur and
some phosphorous.

5. PROPERTIES OF
PROTEINS
• High molecular weight, consisting large
chains of alpha amino acids united in
peptide linkage.
• Proteins contains C,H,O,N and some has P
and S.
• Because of high molecular weight most
proteins are not diffusible through
membranes.

6. • Proteins are generally soluble in water,
weal salt solution, dilate acids and
alkalies.
• Proteins possess free ionic or electrically
charged groups, so that they can migrate
in an electrical field.
• Proteins are used as an antidote for
metallic poisoning.

7. • Proteins are amphoteric substances because
they contains both NH2 and COOH groups.
They can reacts with acids and bases.
• Proteins like albumin and globulin
coagulate on heating.
• All proteins give colour reaction, when
treated with certain reagents.
• All proteins are hydrolysed into their
constituent amino acids by boiling with
acids and alkali.

8. CLASSIFICATION
• Classification based on their physical
properties like solubility and composition.
Accordingly, they are classified into three
main groups.

9. SIMPLE PROTEINS
• On hydrolysis they yueld alpha amino acids
only. The sub groups of simple proteins are
as follows,
• Albumin & Globulin
• Glutelin & Gliadin
• Scleroproteins or Albuminoids
• Histones
• Protoamines

10. 1. Albumin & Globulin
• They coagulate on heating.
• They differ from one another on solubility
(Albumin is soluble in water, whereas
globulin is insoluble in water)
• Sources: { Animal Sources are egg
albumin, myoalbumin, serum albumin
lactalbumin. Egg globulin, myoglobulin,
serum globulin and lactglobulin. }

11. 1. Albumin & Globulin
(Cont...)
• Sources: { Plant Sources are same for both
albumin & globulin. They are legumes of
the peas and beans and in cereals.}

12. 2. Glutelin and Gliadin
• These are present in cereals especially wheat.
• They forms the proteins of the wheat.
• The dough made out of wheat flour contains
starch, glutein and gliadin.
• They contains large amount of glutamic acid.
• Gliadin contains large amount of aminoacid
prolinr and hence it is called as Prolamine.

13. 3. Scleroproteins or
Albuminoids
• They are characterized by great stability
and insolubility in water and salt solutions.
• Since they are essentially similar to albumin
& Globulin they are known as albuminoids.
• They forms most supportive structure of
animals. E.g., Collagen in cartilage, white
fibrous connective tissues, Ossein in bones
and dentine in teeth, keratin in hars and
nails etc.

14. 4. Histones
• They are more complex protamines.
• They are basic proteins and have large
amount of amino acid and histidine.
• They are soluble in water but insoluble in
ammonium hydroxide.
• They occurs in globin of hemoglobin,
nucleoproteins and in spermatazoa of fish.

15. 5. Protamines
• These are simplest of the proteins and
contains about eight amino acids.
• Soluble in water and are not coagulated by
heat.
• They are found in association wit nucleic
acid in the sperm of certain fish.

16. CONJUGATED PROTEINS
• These proteins are composed of simple
proteins combined with some non – proteins
substances known as prosthetic group.
• Classification based on the nature of the
non protein groups to which the proteins
are attached.

17. 2. 1 Nucleoproteins
• These proteins are attached with nucleic
acid.
• They are important compounds in the
protoplasm and nuclei.
• They are also found in chromatin.

18. 2. 2 Phosphoprotein
• These proteins contains phosphoric acid.
• Ecamples: Casein of milk and Vitellin of
Egg.
• They contain 1 % of phosphorous

19. 2. 3 Glycoproteins &
Mucoproteins
• These proteins combines with
carbohydrates like mucopolysaccharides
which includes hyaluronic acid and
chondroitin sulphates.
• The difference between glycoprotein and
mucoprotein is based on the amount of
carbohydrates it contains.
• Present in connective tissues. Tendons
bones and cartilages, synovial fluid and
mucous membrane.

20. 2. 4 Chromoproteins
• These proteins contains certain heterocyclic
compounds like Prophyrins.
• These prophyrins combined with metals
and gives coloured proteins or
chromoproteins.
• Examples: Hemoglobin, Melanoprotein,
Flavoproteins and Chlorophyll.

21. 2. 5 Livoproteins
• These proteins are conjugated with lipids
and fat. Examples phospholipids and
cholesterol.

22. 2. 5 Metalloproteins
• These proteins contains metals as their
prosthetic group. Examples: Ferritin
contains iron, ceruplasmin contains copper.

23. DERIVED PROTEINS
• These proteins are derived from the
simple proteins or conjugated proteins by
the action of acids, alkalies or enzymes.
• They are products resulting from partial to
complete hydrolysis of the proteins.
• Two types of derived proteins are
– Primary derivatives & Secondary derivatives.

24. PRIMARY DERIVATIVES
• They are denaturation products of proteins
resulting from the action of heat, acids and
alkalies on proteins.
• They are heat coagulable,

25. SECONDARY DERIVATIVES
• These proteins are obtained at a later stage
of hydrolysis examples are:
– Proteoses
– Peptones
– Peptides
– Diketopiperazines

26. Proteoses
• Not coagulated by the heat, but precipated
by saturated salt solutions.
• Two types of proteoses
– Primary and secondary proteoses

27. Peptones
• Obtained on further hydrolytic
decompositions.
• Soluble in saturated salt solutions.
• Not coagulated by heat.

28. Peptides & Diketopiperazines
– Peptides
• They are made up of two or more amino
acids and are not coagulated by heat.
– Diketopiperazines
They are cyclic anhydrides of two amino acids.

29. AMINO ACIDS
• They are the simplest units of a protein
molecule and they form the building
blocks of protein structure.

30. • Amino acid consisys of a free NH2 (amino)
and a free COOH (Carboxyl) group. Both are
attached to same carbon atom.
• “R” represents the group other than than
NH2 and COOH groups.
• All amino acids are ∝ - amino acids because
the NH2 group is attached to the ∝ - carbon
atom.

31. CLASSIFICATION OF AMINO
ACIDS
1. Mono amino mono carboxylic acids
2. Mono amino dicarboxylic acids
3. Diamino mono carboxylic acids
4. Sulphur containing amino acids
5. Aromatic amino acids
6. Heterocyclic amino acids
7. Amino acids formed as metabolic
intermediaries

32. 1. MONO AMINO MONO
CARBOXYLIC ACIDS
• Have one amino group and one
carboxylic group.
• They are neutral amino acids.
• EXAMPLES: Glycine, Alanine,
Valine

33. 2. MONO AMINO
DICARBOXYLIC ACIDS
• Contains one amino group and
two carboxyl groups.
• They are acidic amino acids.
• EXAMPLES: Aspartic acid,
Glutamic acid.

34. 3. DIAMINO MONO
CARBOXYLIC ACIDS
• Contains two amino group and
one carboxyl group.
• They are basic amino acids.
• Examples: Arginine, Lysine.

35. 4. SULPHUR
CONTAINING AMINO
ACIDS
• These amino acids contains
aliphatic side chain with sulphate
atoms attached to ∝ - carbon
atoms.
• Examples: Cysteine and Cystine.

36. 5. AROMATIC AMINO
ACIDS
• They contain aromatic rings.
• Examples: Phenylalanine,
Tryptophan, Tyrosine

37. 6. HETEROCYCLIC
AMINO ACIDS
• Contains either imidazole or
indole rings.
• Examples: Proline, Histidine.

38. 7. AMINO ACIDS FORMED AS
METABOLIC INTERMEDIARIES
• These amino acids are formed
during metabolic reactions, they
are physiologically important.
• Examples: Diiodotyrosine and
Thyroxine.

39. USES OF AMINO ACIDS
• They are important dietary sources
of nitrogen.
• Used in protein bio synthesis.
• Serves as a source of energy.
• Used as a source of biosynthesis of
various products. Example: Glycine
is a precursor of creatine,
glutathione, heme, bile acids and
purines.

40. USES OF AMINO ACIDS
(CONT...)
• Aromatic amino acids are the
precursors of thyroid hormones,
catecholamines and melanin.
• Aspartate and glutamate
participate in transamination
reactions.
• Glutamine and Aspartate are used
in the bio – synthesis of purines
and pyrimidines.

41. CHROMATOGRAPHY
• A technique which is used for the
separation and identification of amino
acids in a protein solution.
• In clinical chemistry it is a procedure
applied to separate and identify amino
acids, sugars, lipids, and various other
compounds of clinical interest, present in
urine and other biological fluids.

42. Principles of Chromatography
• In chromatography the
components of mixture
containing amino acids and many
other physiologically important
substances are made to migrate
at different rates in an
apparatus.
• 2 Phases – Stationary Phase and
Moving Phase.

43. Principles of Chromatography
(Cont)
• Stationary Phase – it is the supporting
medium such as filter paper or silica gel on
which the mixture of amino acids are made
to migrate.
• Moving Phase – Consist of a mixture of
immiscible solvent systems, of which one is
usually water which has a stronger affinity
to the supporting medium.

44. TYPES
• PAPER CHROMATOGRAPHY
• GASCHROMATOGRAPHY

45. PAPER CHROMATOGRAPHY
• Most widely procedure for separating and
identification of amino acids.
• Here filter paper is used as a supporting
medium.
• Simple and in expensive procedure.

48. CHROMATOGRAPHY
VIDEO

49. CHROMATOGRAPHY
VIDEO

50. STEPS OF PAPER
CHROMATOGRAPHY
• A strip of filter paper is suspended
vertically with the lower end dipping into a
mixture of water and an organic solvent of
amino acids such as n – butyl alcohol,
phenol or isobutyric acid.

51. • The mixture of water and organic solvent
moves up the filter paper in ascending
chromatogaraphy.
• At the onset of the procedure, a small
quantity of the amino acid mixture is
spotted on the paper at the 5 cm from the
end.
• The paper and the solvent mixture are
enclosed in a curved glass cylinder and
the temperature is maintained constant.

52. • Now the solvent moves up gradually,
goes over the solute spot carrying the
solute along with it.
• Depending upon the solubility of the
solutes contained in the mixtures of
amino acids, the solutes migrates up to
certain distances on the filter paper, at
different rates and afterwards stop
migrating.

53. • But the moving organic solvents still rises up
the paper, leaving behind the solute on the
stationary phase, i.e., paper. Thus other
partition takes place now. The run stops after
some hours.
• The strip of paper is now removed and the
position of the solvent from is marked with a
pencil. The strip is dried and dried with a
solution of ninhydrin in acetone which stains
the amino acid spots purple, thus enabling to
visualize the position of the different amino
acids migrated on the paper strip.

54. • The migration rate of the amino acid is
expressed as Rf value. It is defined as the
ratio of the distance of the spot from the
spotted line to the distance of the solvent
from the spotted line.
Rf Value = Distance of the spot from the
spotted line / Distance of the solvent from the
spotted line.

55. • Rf Value = Distance of the spot from the
spotted line / Distance of the solvent from
the spotted line.