Storage Proteins

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Storage proteins of agricultural seed crops

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Storage Proteins of Food Grains Presented to: Dr. M.K.Mahatama Assistant Professor College of Forestry Navsari Agriculture University Presented by: Navin Chander Gahtyari Msc (Genetics & Plant breeding) N.M.C.A. Navsari Agriculture University

Storage Proteins:

Storage Proteins Generated mainly during seed production and stored in the seed. Serve as nitrogen sources for the developing embryo during germination. The average protein content of:- cereal grains is 10-15 % of their dry weight Leguminosae seeds 20-25%, 3-5 % in normal leaves. can also be found in root and shoot tubers, like in potatoes. They are important for human nutrition.

History:

History Isolation of wheat gluten first being described in 1745 ( Beccari , 1745). TB Osborne ( 1859–1929) is regarded as the father of plant protein chemistry. ' The vegetible proteins ' in 1924. He developed a classification of plant proteins based on their solubility in a series of solvents

Classification based on Solubility:

Classification based on Solubility 1. Albumin: Soluble in H 2 O. 2. Globulin: Soluble in dilute Salt Solution. 3. Prolamines : Soluble in Alcohol e.g. Ethanol 70%(v/v). 4. Glutelins : Soluble in dilute acid or bases.

Storage Globulins:

Storage Globulins The embryo and outer aleurone layer of the endosperm contain globulin storage proteins. Readily soluble in dilute salt solution Sedimentation coefficients of about 7. Usually removed by milling (wheat), polishing (rice), pearling (barley) or decortication (sorghum), before human consumption . Storage globulins of 11–12S located in the starchy endosperm are also present in at least some cereal grains. In fact, in oats and rice these proteins form the major endosperm storage protein fraction.

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Hence Rice & Oats Globulin is related to ‘ legumin ’ type globulin occurring in most dicot seeds. The rice proteins are not readily soluble in dilute salt solutions and hence are classically defined as glutelins , but they clearly belong to the 11–12S globulin family. legumin and vicelin , are present in the seeds of Pisum sativum and that similar proteins can be isolated from the seeds of other leguminoses like Phaseolus vulgaris or Glycine max e.g. Phaseolin

Prolamines:

Prolamines M ajor endosperm storage proteins of all cereal grains(except Rice & Oat) Generally rich in proline and amide nitrogen derived from glutamine. Soluble in alcohol/water mixtures (e.g. 60–70% (v/v) ethanol, 50–55% (v/v) propan‐1‐ol or propan‐2‐ol ) Much more variable in structure than the 7S and 11/12S globulins. Presence in Wheat, Barley, Rye, Maize, Sorghum, Millets. Presence of amino acid sequences consisting of repeated blocks based on one or more short peptide motifs( eg . Methionine , Glycine , Histidine etc.) e.g Zein

Glutelins:

Glutelins Soluble in dilute acids or bases. They are generally prolamine like proteins in certain grass seeds. e.g. Wheat. Glute n in is the most common Glute l in found in Wheat. It imparts baking quality to Wheat.

Gluten:

Gluten Gluten exists in conjugation with starch inside the endosperm of Wheat.

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