Chickpea (Cicer arietinum L.) seed is a potential source of protein ingredients with desirable nutritional and functional properties. Knowledge of molecular characteristics of a food protein is essential before a protein can gain widespread use as a food ingredient. The objectives of this study were to prepare chickpea proteins using different extraction methods and precipitation methods and to investigate molecular characteristics using polyacrylamide gel electrophoresis (PAGE; Native and SDS), reversed phase high performance liquid chromatography (RP-HPLC) and electrospray ionization mass spectrometry (ESI-MS) techniques. Proteins of ground chickpea seed were extracted with sodium hydroxide (NaOH) and with citric acid solutions and precipitated with addition of acid and by cryoprecipitation. The protein contents of the protein preparation ranged from 49% to 97%. The microstructures of chickpea protein isolates examined by scanning electron microscope (SEM) revealed the presence of starch grains in the cryoprecipitates from citric acid extraction but not in isoelectric precipitates. The globulins (legumins and vicilins), glutelins, and albumins from both citric acid and NaOH isolates were characterized by Native-PAGE. The cryoprecipitates contained mainly the globulin-rich proteins. With SDS-PAGE characterization, protein subunits were identified as follows: (i) legumin subunits: MW 40, 39, 26, 23, and 22 kDa, (ii) vicilin subunits: MW 50, 37, 33, 19, and 15 kDa, (iii) glutelin subunits: 58, 55, and 54 kDa, and (iv) albumin subunits: 10 kDa. Separation of fractions of isolated chickpea proteins by RP-HPLC showed that early eluting fractions (Rt 20-30 min) consisted of subunits of MW 6.5-31 kDa (SDS-PAGE). At elution time 30-36 min, the fractions obtained were composed mainly of mixtures of legumin and vicilin subunits (MW 14-45 kDa). The major subunits of chickpea protein fractions from both cryoprecipitates and isoelectric precipitates are legumin basic subunit (MW∼23 kDa) and vicilin-rich proteins (MW∼19, 17, 15 kDa). ESI-MS analysis of fractions separated by RP-HPLC showed MW ranging between 5.1 and 53.5 kDa. The subunits of MW 35366, 27626, 22864, 20531, 16092, and 15626 Da of fractions from ESI-MS corresponded to MW 35.3, 28.0, 24.1, 20.5, 16.1, and 15.3 kDa identified in SDS-PAGE. These fractions were identified as legumin-rich and vicilin-rich proteins.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.115839 |
| Date | January 2006 |
| Creators | Chang, Yu-Wei, 1977- |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Food Science and Agricultural Chemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002484003, proquestno: AAIMR24634, Theses scanned by UMI/ProQuest. |
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