Type of Document Thesis Author Jayasena, Shyamali H. Author's Email Address email@example.com URN etd-07232011-132713 Title Purification and Characterization of Select Glycoproteins of Almonds (Prunus dulcis L.) Degree Master of Science Department Nutrition, Food, and Exercise Science, Department of Advisory Committee
Advisor Name Title Kenneth H. Roux Committee Member Shridhar K. Sathe Committee Member Yun-Hwa Peggy Hsieh Committee Member Keywords
- Hydroxynitrile lyase
- Prunasin hydrolase
Date of Defense 2011-06-27 Availability unrestricted AbstractAlmonds (Prunus dulcis L.) are the most widely consumed tree nuts in the USA besides USA also being the number one global producer of almonds. Although almonds can be consumed without any adverse effects by the majority of the population, a few susceptible individuals develop allergic symptoms following the ingestion of almonds. Almond allergies are the third most common of all tree nut allergies, affecting ~15% of the tree nut allergic population in the USA. Several proteins of almonds have been identified as being allergenic, including almond major protein (AMP) or amandin which is a major allergen of almonds. However, although several glycoproteins of almonds have been biochemically characterized, the potential allergenicity of most almond glycoproteins are yet to be elucidated. In the present study select almond glycoproteins were partially purified and characterized.
Glycoproteins which comprise less than 2% of the total soluble proteins of almonds were purified and separated from the non-glycoprotein fraction using affinity chromatography and were further resolved in to 3 peaks when passed through a gel filtration column. The 3 glycoprotein peaks (glycoproteins A, B and C) were partially characterized biochemically and immunologically in this study.
SDS- PAGE analysis under reducing conditions showed that both glycoproteins A and B had 3 major peptide bands in addition to several minor peptides. The 3 major bands of glycoprotein A had molecular masses of ~13 kDa, ~22 kDa and ~44 kDa. The major peptides of glycoprotein B were found to have molecular weights of ~12 kDa, ~34 kDa and ~62 kDa. Glycoprotein C was composed of a single major peptide of ~62 kDa and also of several minor peptides ranging from ~11 kda to ~55 kDa. The major peptides at ~62 kDa of glycoproteins B and C were identified as prunasin hydrolase and hydroxynitrile lyase, respectively by N-terminal amino acid sequencing.
All three glycoproteins A, B and C were immunoreactive with polyclonal antibodies raised against whole almonds in rabbit. However, none of the 3 glycoproteins were recognized by the monoclonal antibodies 4C10 and 4F10 raised against AMP of almonds. Dot blot analysis of glycoproteins with human IgE from almond allergic patients resulted in the recognition of glycoprotein B by 6 of the 11 (53%) patient sera tested. 3 of the 11 samples (27%) reacted with glycoprotein A while most patient sera did not show any reactivity with glycoprotein C. Deglycosylation resulted in a significant loss of immunoreactivity of all 3 glycoproteins indicating the possibility of carbohydrate moieties playing a role in their immunoreactivity.
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