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Title: Relationship between digestive enzymes, proteins and anti-nutritive factors in monogastric digestion
Author: Kempapidis, Theofilos
ISNI:       0000 0004 9358 3339
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2019
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Monogastrics’ lack of some digestive enzymes is compensated by using exogenous enzymes in the animal feed. Those interact with feed ingredients causing enzyme inhibition. Two known inhibiting substances are phytic acid and polyphenolics. Phytase is an important exogenous enzyme that is breaking down phytic acid. The effect of sorghum polyphenolic-rich extracts on the 6-phytase activity was investigated using an ITC by calculating its relative activity. Results show inhibition of the phytase, from all three extracts. For a better understanding of this assay, a real-time mass spectroscopic analysis was performed, that showed the pattern in which the phytase is hydrolysing phytic acid. Consecutively, the effect of phytic acid on the activity of three proteases exogenous and endogenous chymotrypsin and endogenous trypsin was studied. A colorimetric assay using casein as a substrate was used. The results showed different levels of inhibition of all three enzymes by phytic acid. Finally, the interaction between the exogenous chymotrypsin and the phytase was studied by using the ITC enzyme assay and an SDS-Page gel analysis. ITC results showed partial inhibition of the phytase activity, while SDS-Page results showed complete inhibition. Literature supports the results of this study which can have a negative nutritional and economic effect. This information could be used to create a conceptual model, that would be a useful tool to understand the fundamental interactions of enzymes, substrates and anti-nutritive factors in order to improve monogastrics’ nutrition.
Supervisor: Falconer, Robert ; Cameron, Duncan Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available