Isolation and Characterization of Chickpea (Cicer arietinum L.) Seed Protein Fractions

Proteins of ground chickpea seeds were extracted with sodium hydroxide (NaOH) solution and precipitated with addition of acid (isoelectric precipitate (C-IP)) and by cryoprecipitation (cryoprecipitate (C-CP)). The protein isolates were characterized by Native PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), reversed-phase high performance liquid chromatography (RP-HPLC) and electrospray-ionization mass spectrometry (ESI/MS). Both the isoelectric precipitate and cryoprecipitate contained the globulin protein 11S legumins and 7S vicilins as the major protein fractions and 2S albumin proteins as a minor protein fraction. The major subunits of RP-HPLC protein fractions from both cryoprecipitate and isoelectric precipitate were found to contain subunits of both legumins and vicilins. SDS-PAGE identified legumin alpha-subunits with MW 40.6 and 39.5 kDa and legumin beta- subunits with MW 23.5 and 22.5 kDa, and vicilin subunits with MW 70.2, 50.7, 35.0, 33.6, 18.9 and 15.5 kDa. ESI-MS molecular weights 35,366, 35,268 and 14,648 Da are likely vicilin subunits while the 24,894 Da is a legumin beta-subunit.