Chromatographic separation, fractionation and oxidation of selected beta-lactoglobulin peptides

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http://urn.fi/URN:NBN:fi:hulib-201507211768
Title: Chromatographic separation, fractionation and oxidation of selected beta-lactoglobulin peptides
Author: Gürbüz, Göker
Contributor: University of Helsinki, Faculty of Agriculture and Forestry, Department of Food and Environmental Sciences
Publisher: Helsingfors universitet
Date: 2010
Language: eng
URI: http://urn.fi/URN:NBN:fi:hulib-201507211768
http://hdl.handle.net/10138/24771
Thesis level: master's thesis
Discipline: Food Science
Food Science (Food Safety)
Food Science
Abstract: The literature review elucidates the mechanism of oxidation in proteins and amino acids and gives an overview of the detection and analysis of protein oxidation products as well as information about ?-lactoglobulin and studies carried out on modifications of this protein under certain conditions. The experimental research included the fractionation of the tryptic peptides of ?-lactoglobulin using preparative-HPLC-MS and monitoring the oxidation process of these peptides via reverse phase-HPLC-UV. Peptides chosen to be oxidized were selected with respect to their amino acid content which were susceptible to oxidation and fractionated according to their m/z values. These peptides were: IPAVFK (m/z 674), ALPMHIR (m/z 838), LIVTQTMK (m/z 934) and VLVLDTDYK (m/z 1066). Even though it was not possible to solely isolate the target peptides due to co-elution of various fractions, the percentages of target peptides in the samples were satisfactory to carry out the oxidation procedure. IPAVFK and VLVLDTDYK fractions were found to yield the oxidation products reviewed in literature, however, unoxidized peptides were still present in high amounts after 21 days of oxidation. The UV data at 260 and 280 nm enabled to monitor both the main peptides and the oxidation products due to the absorbance of aromatic side-chains these peptides possess. ALPMHIR and LIVTQTMK fractions were oxidatively consumed rapidly and oxidation products of these peptides were observed even on day 0. High rates of depletion of these peptides were acredited to the presence of His (H) and sulfur-containing side-chains of Met (M). In conclusion, selected peptides hold the potential to be utilized as marker peptides in ?-lactoglobulin oxidation.
Subject: B-Lactoglobulin
protein oxidation
peptides
HPLC
beta-lactoglobulin
elintarviketieteet
valkuaisaineet
pilaantuminen
peptidit
fraktiointi
hapettuminen
proteiinit
elintarviketurvallisuus


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