{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/121222"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/121222","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Effects of functional group-specific complexation and adsorption of phytic acid on its degradation by phytase","abstract":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2025-08-01","abstract_html":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2025-08-01","abstract_has_math":false,"creators":["Chen, Ai"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Natural Res & Env Sciences","degree_department":null,"school":null,"contributors":["Arai, Yuji","Mulvaney, Richard","Han, Hee-Sun","Zhu, Lingyang"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2023,"date_issued":"2023-08","date_published":"2023-08","updated_at":"2026-07-22T22:24:57Z","subjects":["Phosphorus","Mineralization","Nmr","Calcite","Phytase"],"languages":["en","eng"],"rights":["Copyright 2023 Ai Chen"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/121222","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Arai, Yuji","Mulvaney, Richard","Han, Hee-Sun","Zhu, Lingyang"]},{"key":"dc:creator","label":"Author","values":["Chen, Ai"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2023-08","2023-07-07"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Natural Res & Env Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Phosphorus","Mineralization","Nmr","Calcite","Phytase"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2023 Ai Chen"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/121222"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2025-08-01","The student, Ai Chen, accepted the attached license on 2023-07-06 at 12:23.","The student, Ai Chen, submitted this Dissertation for approval on 2023-07-06 at 12:32.","This Dissertation was approved for publication on 2023-07-07 at 16:09.","DSpace SAF Submission Ingestion Package generated from Vireo submission #19535 on 2023-12-04 at 17:31:23","As one of the most predominant organic phosphorus (P) species in many soils, phytic acid could serve as a potentially important mineralizable P reservoir in soils and sediments. However, the active interaction between phytic acid and metals or minerals has rendered phytic acid recalcitrant against mineralization. The mechanisms of phytic acid adsorption on the calcite-water interface haven’t been clearly investigated. Furthermore, how phytic acid-Ca2+, or phytic acid-calcite interaction affects the activity of phytase, a group of enzymes that can mineralize phytic acid, remains unclear. This study, therefore, investigated the adsorption mechanism of phytic acid at the calcite-water interface, and how Ca2+ (aq) or calcite affected phytase activity using different spectroscopic techniques. Phytic acid was predominantly adsorbed via outer-sphere complexation at pH 6 and pH 8, which was supported by: i) a lack of significant change in the zeta potential of phytic acid reacted-calcite; and ii) a fast exchange between free phytic acid and adsorbed phytic acid. The results also showed functional group specificity of phytic acid and phytic acid structural change during the adsorption. Batch degradation kinetic experiments showed that phytase activity followed Michaelis-Menten kinetics at pH 6, and the increased Km and decreased Vmax with Ca2+/calcite addition indicated a mixed inhibition mechanism, which was likely due to the allosteric effects of Ca2+/calcite, which altered the phytase secondary structure. The phytase used in this study was also observed to target the phosphate at the D/L-3 position on a phytic acid molecule at pH 6. The overall phytase activity decreased at pH 8 due to the denaturing effect of the alkaline pH, while Ca2+/calcite addition enhanced phytase activity, which was attributed to the structural change of phytic acid upon complexation. Additionally, in the case of calcite, the stabilization of phytase conformation when interacting with the mineral interface also contributed to enhanced activity. Contrary to what was observed at pH 6, the target of phytase was P5 at pH 8. Consequently, the solubility, mineralization, and bioavailability of phytic acid in soils rich in calcite largely depend on the mutual interaction among phytic acid, phytase, and Ca2+ (aq)/calcite, which is affected by soil conditions (e.g., pH, solution composition)."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Effects of functional group-specific complexation and adsorption of phytic acid on its degradation by phytase"]}]}],"canonical_facts":{"dc:contributor":["Arai, Yuji","Mulvaney, Richard","Han, Hee-Sun","Zhu, Lingyang"],"dc:creator":["Chen, Ai"],"dc:date":["2023-08","2023-07-07"],"dc:description":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2025-08-01","The student, Ai Chen, accepted the attached license on 2023-07-06 at 12:23.","The student, Ai Chen, submitted this Dissertation for approval on 2023-07-06 at 12:32.","This Dissertation was approved for publication on 2023-07-07 at 16:09.","DSpace SAF Submission Ingestion Package generated from Vireo submission #19535 on 2023-12-04 at 17:31:23","As one of the most predominant organic phosphorus (P) species in many soils, phytic acid could serve as a potentially important mineralizable P reservoir in soils and sediments. However, the active interaction between phytic acid and metals or minerals has rendered phytic acid recalcitrant against mineralization. The mechanisms of phytic acid adsorption on the calcite-water interface haven’t been clearly investigated. Furthermore, how phytic acid-Ca2+, or phytic acid-calcite interaction affects the activity of phytase, a group of enzymes that can mineralize phytic acid, remains unclear. This study, therefore, investigated the adsorption mechanism of phytic acid at the calcite-water interface, and how Ca2+ (aq) or calcite affected phytase activity using different spectroscopic techniques. Phytic acid was predominantly adsorbed via outer-sphere complexation at pH 6 and pH 8, which was supported by: i) a lack of significant change in the zeta potential of phytic acid reacted-calcite; and ii) a fast exchange between free phytic acid and adsorbed phytic acid. The results also showed functional group specificity of phytic acid and phytic acid structural change during the adsorption. Batch degradation kinetic experiments showed that phytase activity followed Michaelis-Menten kinetics at pH 6, and the increased Km and decreased Vmax with Ca2+/calcite addition indicated a mixed inhibition mechanism, which was likely due to the allosteric effects of Ca2+/calcite, which altered the phytase secondary structure. The phytase used in this study was also observed to target the phosphate at the D/L-3 position on a phytic acid molecule at pH 6. The overall phytase activity decreased at pH 8 due to the denaturing effect of the alkaline pH, while Ca2+/calcite addition enhanced phytase activity, which was attributed to the structural change of phytic acid upon complexation. Additionally, in the case of calcite, the stabilization of phytase conformation when interacting with the mineral interface also contributed to enhanced activity. Contrary to what was observed at pH 6, the target of phytase was P5 at pH 8. Consequently, the solubility, mineralization, and bioavailability of phytic acid in soils rich in calcite largely depend on the mutual interaction among phytic acid, phytase, and Ca2+ (aq)/calcite, which is affected by soil conditions (e.g., pH, solution composition)."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/121222"],"dc:language":["en","eng"],"dc:rights":["Copyright 2023 Ai Chen"],"dc:subject":["Phosphorus","Mineralization","Nmr","Calcite","Phytase"],"dc:title":["Effects of functional group-specific complexation and adsorption of phytic acid on its degradation by phytase"],"dc:type":["text"],"thesis:degree_discipline":["Natural Res & Env Sciences"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:57Z"}