Tuesday, July 04, 2006



The simplest criterion used for the characterization of proteins is their solubility in various media. As in all legumes, the bulk of soybean proteins are globulins, characterized by their solubility in salt solutions. The solubility of soybean proteins in water is strongly affected by the pH. Close to 80 % of the protein in raw seeds or unheated meal can be extracted at neutral or alkaline pH. As the acidity is increased, solubility drops rapidly and a minimum is observed at pH 4.2 to 4.6. This is the isoelectric region of soybean proteins taken as a whole.
The pH dependence of solubility is used in the manufacture of isolated soybean protein, whereby defatted, unheated meal is extracted with water at neutral or slightly alkaline pH, and the protein is then precipitated from the filtered extract by acidification to the isoelectric region.
More precise and detailed fractionation of the proteins can be carried-out by techniques such as ultracentrifugation, gel filtration and electrophoresis.
Since the classical work of W. Wolff, it has become customary to characterize the soybean protein fractions by their sedimentation constants.

Four major fractions, known as 2 S, 7 S, 11 S and 15 S have been studied extensively. (S stands for Svedberg units. The numerical coefficient is the characteristic sedimentation constant in water at 20oC. The figures are not exact but nominal. Thus the 11 S globulin has a sedimentation constant of 12.3). The 11 S and 7 S fractions constitute about 70% of the total protein in soybeans. The ratio 11 S/7 S is a varietal characteristic and may vary from 0.5 to 3.

The 2 S fraction consists of low molecular weight polypeptides (in the range of 8000 to 20000 daltons) and comprises the soybean trypsin inhibitors (see below).

The 7 S fraction is highly heterogeneous. Its principal component is beta-conglycinin, a sugar containing globulin with a molecular weight in the order of 150000. The fraction also comprises enzymes (beta-amylase and lipoxygenase) and hemagglutinins (see below ).

The 11 S fraction consists of glycinin, the principal protein of soybeans. Glycinin has a molecular weight of 320000-350000 and is built of 12 sub-units, associated through hydrogen bonding and disulfide bonds. The ability of soy proteins to undergo association-dissociation reactions under known conditions, is related to their functional properties and particularly to their texturization.

The 15 S protein is probably a dimer of glycinin. Conglycinin and glycinin are storage proteins and they are found in the protein bodies within the cells of the cotyledons.


Some of the problems associated with soybean proteins include
(1) presence of anti-nutritional factors such as trypsin inhibitor,
(2) undesirable beany flavor,
(3) elicitation of allergic reactions in susceptible individuals,
(4) poor digestibility of soybean proteins, and
(5) deficiency in sulfur-containing amino acids.


Research Plan 2005

Genetic Transformation of Soybean (Glycine max Merril L) Via Particle Bombardment

The quick and best method to achieve genotype independent transformation in crops is the delivery of foreign DNA directly into regenerative cells. Micro projectile bombardment also known as particle bombardment or biolistics is presently used in researches to produce stably transformed plants in many economically important crops. It employs high velocity metal (gold or tungsten) particles to deliver biologically active DNA into targeted, published results show that embryonic or meristematic tissues are more transformable and are able to regenerate into transgenic plants. Transient gene expression can be observed in differentiated plant tissues, the expression of foreign genes is examined by visual and quantitative methods and the study of gene responsible for plant ontogeny can be possible.


The objective of the research is to improve the protein quality in soybean through particle bombardment.

Materials and Methods

Plant material
Preparation of recombinant Plasmid DNA
Isolation of plasmid DNA
Preparation of genomic DNA from Soybean Plant tissue
Identification, Isolation and cloning of genes responsible for coding beta conglycinin
(7S) and glycinin (11S) proteins
Preparation of recombinant plasmid DNA (Plasmid DNA and gene of Interest)
Somatic embryogenesis of soybean seed, Proliferation of tissue
Histochemical analysis
Selection for transgenic
PCR, Southern Blot hybridization
Development and maturation of embryo,
Desiccation and germination

Monday, July 03, 2006




Credits: http://in.news.yahoo.com/040318/43/2c240.html