Presentation of protein properties and types.pdf

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1. Presentation topic:
Properties of protein
Presented by Shiza Sehar & Nimra Nawaz

2. Some general
properties of
protein are:
1.Taste
2.Odour
3.Molecular weight
4.Viscosity of protein solution
5.Hyderation of protein
6.Heat coagulation of protein
7.Amphoteric nature

3. The detail of these properties are
mentioned below:

4. 8: precipitation of protein:
Precipitation by positive ions(+ve)
Precipitation by negative ions(-ve)

5. Taste:
They are usually tasteless but
hydrolytic products are bitter in
taste.

6. Odour:
Odourless
But when heated to dryness they
turn brown and give of the odour of
burning feather.

7. Molecular
weight:
General have a large molecular
weight therefore they are known as
macromolecules
Molecular weight can be measured
by physical methods like,
X Ray diffraction
Light scattering effect

8. Viscosity
of protein
solution:
Vary widely with the kind of protein
and concentration in solution
Viscosity closely related to
molecular shape, long molecules
(fibrous protein) being more viscous
than globular proteins.

9. Hydration
of protein:
Polar groups of protein -NH2 & -
COOH become hydrated in presence
of H2O and swell up when
electrolytes such as alcohol or sugar
that form complexes in water are
added to protein solution.

10. Heat
coagulation
of protein:
Several proteins coagulate forming
coagulum
Coagulation Is maximum at
isoelectric PH
During coagulation protein
undergoes a change called as
denaturation.
Denatured protein are soulble in
extreme PH

11. Amphoteric
nature of
protein:
In protein amino acids carry –COOH
andamino group in their side chains
These groups can produce both
anions and cations in solution
Therefore proteins are ampholytes
and act as both acids and bases
At specific pH called isoelectric PH a
protein exists as a dipolar ion or
zwitterion carrying equal no of
positive & negative charge

12. Precipitation
of proteins:
Precipitation of protein by +ve
ions:
Positive ions most commonly used
are those of heavy metals such as
Zn, Fe,Cu,Pb
These metals precipitate protein at
the pH alkaline to its isoelectric PH
At this pH, proteins is dissociated as
an anion protienate.

13. The metal ion combine with the
-COO- group giving insoluble
precipitate of metal protienate.

14. Negative ion
precipitation:
Negative ions combine with protein
when the pH of the medium is on
the acidic side of its isoelectric PH
Acidic pH makes protein to exist as
protien+ and form precipitate with
-ve ions .