2. • What is seed storage protein?
Roles -
Classification-
Summary-
3. * The plant seed is not only the organ of
propagation and dispersion but also harvested
by humans.
* The amount of protein present in the seed varies
from ~10%(in cereals) to ~40 % (in legumes and
oilseeds ) .
4.
5. Majority of protein in seed perform either
metabolic or structural roles.
Storage of Amino acids for use during seed
germination and seedling growth.
Nutritional value of seed.
Plays role in defense mechanisms.
Source of Sulphur and Nitrogen.
6. •Synthesis at high level in specific tissues and at
certain stage of development.
•In mature seed found in discrete deposits called
protein bodies.
7. Classified on the basis of solubility by T.B.
Osborne:-
Soluble in Dilute saline solution......Globulins
Soluble in Alcohols............................Prolamins
Soluble in Dilute Acids......................Glutelins
Soluble in water.................................Albumins
8.
9. The embryo and outer aleuronic layer of the
endosperm contain globulin storage protein.
They are present in dicot, monocots(including cereals
and palms) and fern spores .
They can be divided into two groups based on their
sedimentation coefficients :
I. 7S Viclilin-type globulins
II. 11S Legumin-type globulins
10. Both groups show considerable variation in their
structures resulting partly from post-translational
processing.
Globulin are defecient in cyctein and metheonine but
11S globulin are rich in these both amino acids.
11. The rice protein are no readily soluble in dilute salt
solution and hence classically define as glutelins ;but
they clearly belong to the 11S to 12S globulin family.
Legumin and Viclilin are present in Pisum sativum
and that similar protein can be isolated from other
leguminous plant like Phaseolus Vulgaris(Flat bean).
12.
13. Major endosperm storage protein (~50% )of all cereal
grains except rice and oats (~5% to 10% ).
Prolamins are restricted to the family of grasses.
Prolamins usually account for approximately half of the
total grain nitrogen.
Prolamins are recognized on the basis of their solubility in
alcohol and their high levels of glutamine and proline.
14. In prolamins, amino acid sequences are present consisting
of repeated unit of Metheonine ,Glycine ,Histamine.
E.g.: Zein in maize
Protect seed against
microbial attack.
• The α-Zeins of Maize account for ~75 to 80% of the total
prolamins in maize.
• They have structures consisting of repeated sequences of
unique N- and C-terminal domains
15.
16. They are generally prolamins like protein in certain
grass(monocot) seed.
Glutelins are the seed storage protein in mature wheat
seeds (closely related species).
It is the sticky substance in wheat which allows dough to
rise and retain its shape during baking.
Glutelins are the primary energy storage in the endosperm
of rice.
17. There are typically high-molecular-weight (HMW)
and low-molecular-weight (LMW) glutelins in
different species.
They crosslink with themselves and other proteins
during baking via disulfide bonds.
18.
19. Sedimentation coefficient of Albumin is 2S.
They are widely distributed in dicot seeds and have
been most widely studied in the Brassicaceae, notably
oil- seed rape and Arabidopsis.
2S albumins are compact globular proteins with
conserved cysteine residues.
20. 2S albumins can also play a protective role in plants as
defensive weapons against fungal attack .
The amino acid composition of 2S albumin proteins
from many plant species has revealed their high
content of sulphur-containing amino acids .
21. Seed is the organ of propagation ,protein content
of seed is 40%(leguminous and oil seed) to
10%(cereals).
Perform metabolic , structural, defensive role.
Provide nitrogen , sulphur, carbon to seed.
Classified on the basis of solubility into four types
albumin, globulin, prolamins, glutelins etc.
Globulins present in both dicot ,monocot and fern
spores. And of two types 7Sand 11S globulin.
22. Prolamins are major Nitrogen source of seed and
present in monocots only.
Zein protein maize protects seed from microbial
attack
Glutelins are globulin (11S to 12S) which are not
soluble in dilute saline solution.
Present in the monocot seeds.
Albumins are important source of sulphur and
protects seed form fungal attack.
