Structural and functional characterization of yellow field pea (Pisum sativum) soluble protein aggregates and cholinesterase-inhibitory peptides

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dc.contributor.authorAsen, Nancy D.
dc.contributor.examiningcommitteeUdenigwe, Chibuike (Food and Human Nutritional Sciences)en_US
dc.contributor.examiningcommitteeKoksel, Filiz (Food and Human Nutritional Sciences)en_US
dc.contributor.examiningcommitteeMarcone, Massimo (University of Guelph)en_US
dc.contributor.supervisorAluko, Rotimi
dc.date.accessioned2023-03-24T20:21:02Z
dc.date.available2023-03-24T20:21:02Z
dc.date.copyright2023-03-15
dc.date.issued2023-03-07
dc.date.submitted2023-03-16T04:15:15Zen_US
dc.degree.disciplineFood and Human Nutritional Sciencesen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractThis thesis determined the structure - function properties of soluble protein aggregates and acetylcholinesterase and butyrylcholinesterase-inhibitory peptides (CEI) prepared from yellow pea protein (YFP) respectively. To obtain the soluble aggregates, a commercial YFP protein concentrate (PPC) was heated at different pH values and the supernatant was sequentially passed through 30 and 50 kDa molecular weight cut-off membranes to collect the <30, 30 – 50, and >50 kDa fractions. The >50 kDa fractions had high protein contents (>60%) among the fractions and were collected to determine their physicochemical properties and functionality in food systems. The morphological structure of the protein samples and emulsion microstructures showed that heat treatment of the samples at different pH values produced different protein aggregates under varying processing conditions. Treatments at pH 3.0 produced aggregates with better solubility at acidic pH as well as superior emulsifying and foaming properties. Secondly, the CEI peptides were prepared by enzymatic digestion of PPC into protein hydrolysates using six proteases. Peptide fractions from the digests were obtained by membrane ultrafiltration (UF) and reverse-phase HPLC separation, which was followed by mass spectroscopy where the mass to charge ratios were obtained to identify the peptide sequence and de novo synthesis was carried out. Antioxidant properties as well as cholinesterase inhibitory activities of the hydrolysates, peptide fractions, and synthesized peptides were determined. Hydrolysates obtained from alcalase, flavourzyme and pepsin exhibited significantly (p < 0.05) higher (20-30% increases) CEI and radical scavenging activities than the other hydrolysates and the potency increased (>10%) after UF or HPLC separation. The interaction between the peptide and cholinesterases was confirmed using intrinsic fluorescence and circular dichroic spectra. Mixed mode inhibition was exhibited by most of the peptides against the cholinesterases and molecular docking assay revealed that most peptides were bound to cholinesterases through the catalytic anionic site or the peripheral anionic site with low docking energy scores. The structure-function relationship as determined by PLS modeling showed that the most potent CEI peptides mostly contained polar, slightly polar, and neutral amino acids like aspartic acid, threonine, alanine, proline, valine, arginine, histidine, and leucine.en_US
dc.description.noteMay 2023en_US
dc.description.sponsorshipNSERC CREATE CAPTURE Programen_US
dc.identifier.urihttp://hdl.handle.net/1993/37219
dc.language.isoengen_US
dc.rightsopen accessen_US
dc.subjectYellow field peaen_US
dc.subjectProteinen_US
dc.subjectFunctional propertiesen_US
dc.subjectHeaten_US
dc.subjectUltrafiltrationen_US
dc.subjectaggregatesen_US
dc.subjectAlzheimer's diseaseen_US
dc.subjectCholinesteraseen_US
dc.subjectPeptidesen_US
dc.subjectInhibitionen_US
dc.subjectQSARen_US
dc.subjectMolecular dockingen_US
dc.titleStructural and functional characterization of yellow field pea (Pisum sativum) soluble protein aggregates and cholinesterase-inhibitory peptidesen_US
dc.typedoctoral thesisen_US
local.subject.manitobayesen_US
oaire.awardNumberRGPIN 2018-06019en_US
project.funder.identifierNSERC: https://doi.org/10.13039/501100000038en_US
project.funder.nameNatural Sciences and Engineering Research Council of Canadaen_US
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