Phosphate buffer saline pH=7-7.5 is the best. make sure its chilled to keep the protein intact for PAGE analysis if you wish to do it.

Best of Luck

Dear Sonia Afrin,

You can measure total proteins using Bradford method. You can search this method and find different paper that uses this method.

Wishing you the best,

Dear sonia afrin 

Extracting the protein from the seeds and deposition on the basis of change in the pH of amidst the extraction (oil extracted from the seeds first and then extracted protein)

( joshi and nigam 1976 )

DEPENDING ON THE SEED TYPE TRY TO DE-FATTEN THE SEED FIRST FOLLOWED BY EXTRACTION WITH TRIS-HCL BUFFER

Inclusion of NaCl in your buffer, perhaps 0.1 M, also helps in solubilizing the storage globulins.

First defat the sample and try extraction tris-hcl buffer pH 8...

You can do fractionation by using different solutions like

Water for albumin fraction

salt(NaCl) for globulin fraction

Alcohol for prolamin fraction

Acid/Alkali for glutelin fraction