Comparison of Interactions Between Soy Protein Isolate and Three Folate Molecules: Effect on the Stabilization, Degradation, and Oxidization of Folates and Protein

This study selected three approved folate sources—folic acid (FA), L-5-methyltetrahydrofolate (MTFA), and calcium 5-methyltetrahydrofolate (CMTFA)—to explore their interaction mechanisms with soy protein isolate (SPI) through spectrofluorometric analysis and molecular docking simulations. We investi...

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Main Authors: Linlin He, Yuqian Yan, Dandan Song, Shuangfeng Li, Yanna Zhao, Zhuang Ding, Zhengping Wang
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Foods
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Online Access:https://www.mdpi.com/2304-8158/13/24/4033
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author Linlin He
Yuqian Yan
Dandan Song
Shuangfeng Li
Yanna Zhao
Zhuang Ding
Zhengping Wang
author_facet Linlin He
Yuqian Yan
Dandan Song
Shuangfeng Li
Yanna Zhao
Zhuang Ding
Zhengping Wang
author_sort Linlin He
collection DOAJ
description This study selected three approved folate sources—folic acid (FA), L-5-methyltetrahydrofolate (MTFA), and calcium 5-methyltetrahydrofolate (CMTFA)—to explore their interaction mechanisms with soy protein isolate (SPI) through spectrofluorometric analysis and molecular docking simulations. We investigated how these interactions influence the structural and physicochemical stability of folates and SPI. Three folates spontaneously bound to SPI, forming complexes, resulting in a decrease of approximately 30 kJ·mol<sup>−1</sup> in Gibbs free energy and an association constant (K<sub>a</sub>) of 10<sup>5</sup> L·mol<sup>−1</sup>. The thermodynamic parameters and molecular docking study revealed the unique binding mechanisms of FA and MTFA with SPI. FA’s planar pteridine ring and conjugated double bonds facilitate hydrophobic interactions, whereas MTFA’s reduced ring structure and additional polar groups strengthen hydrogen bonding. Although the formation of SPI–folate complexes did not result in substantial alterations to the SPI structure, their binding has the potential to enhance both the physical and thermal stability of the protein by stabilizing its conformation. Notably, compared with free FA, the FA-SPI complexes significantly enhanced FA’s stability, exhibiting 71.1 ± 1.2% stability under light conditions after 9 days and 63.2 ± 2.6% stability in the dark after 60 days. In contrast, no similar effect was observed for MTFA. This discrepancy can be ascribed to the distinct degradation pathways of the Fa and MTFA molecules. This study offers both theoretical and experimental insights into the development of folate-loaded delivery systems utilizing SPI as a matrix.
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spelling doaj-art-1c8d7d9d7d044be782147ff97dd06c972025-08-20T02:43:29ZengMDPI AGFoods2304-81582024-12-011324403310.3390/foods13244033Comparison of Interactions Between Soy Protein Isolate and Three Folate Molecules: Effect on the Stabilization, Degradation, and Oxidization of Folates and ProteinLinlin He0Yuqian Yan1Dandan Song2Shuangfeng Li3Yanna Zhao4Zhuang Ding5Zhengping Wang6Institute of Biopharmaceutical Research, Liaocheng University, Liaocheng 252059, ChinaInstitute of Biopharmaceutical Research, Liaocheng University, Liaocheng 252059, ChinaInstitute of Biopharmaceutical Research, Liaocheng University, Liaocheng 252059, ChinaSchool of Pharmaceutical Science and Food Engineering, Liaocheng University, Liaocheng 252059, ChinaInstitute of Biopharmaceutical Research, Liaocheng University, Liaocheng 252059, ChinaInstitute of Biopharmaceutical Research, Liaocheng University, Liaocheng 252059, ChinaInstitute of Biopharmaceutical Research, Liaocheng University, Liaocheng 252059, ChinaThis study selected three approved folate sources—folic acid (FA), L-5-methyltetrahydrofolate (MTFA), and calcium 5-methyltetrahydrofolate (CMTFA)—to explore their interaction mechanisms with soy protein isolate (SPI) through spectrofluorometric analysis and molecular docking simulations. We investigated how these interactions influence the structural and physicochemical stability of folates and SPI. Three folates spontaneously bound to SPI, forming complexes, resulting in a decrease of approximately 30 kJ·mol<sup>−1</sup> in Gibbs free energy and an association constant (K<sub>a</sub>) of 10<sup>5</sup> L·mol<sup>−1</sup>. The thermodynamic parameters and molecular docking study revealed the unique binding mechanisms of FA and MTFA with SPI. FA’s planar pteridine ring and conjugated double bonds facilitate hydrophobic interactions, whereas MTFA’s reduced ring structure and additional polar groups strengthen hydrogen bonding. Although the formation of SPI–folate complexes did not result in substantial alterations to the SPI structure, their binding has the potential to enhance both the physical and thermal stability of the protein by stabilizing its conformation. Notably, compared with free FA, the FA-SPI complexes significantly enhanced FA’s stability, exhibiting 71.1 ± 1.2% stability under light conditions after 9 days and 63.2 ± 2.6% stability in the dark after 60 days. In contrast, no similar effect was observed for MTFA. This discrepancy can be ascribed to the distinct degradation pathways of the Fa and MTFA molecules. This study offers both theoretical and experimental insights into the development of folate-loaded delivery systems utilizing SPI as a matrix.https://www.mdpi.com/2304-8158/13/24/4033soy proteinfolic acidL-5-methyltetrahydrofolatenon-covalent interactionsstabilitydegradation pathway
spellingShingle Linlin He
Yuqian Yan
Dandan Song
Shuangfeng Li
Yanna Zhao
Zhuang Ding
Zhengping Wang
Comparison of Interactions Between Soy Protein Isolate and Three Folate Molecules: Effect on the Stabilization, Degradation, and Oxidization of Folates and Protein
Foods
soy protein
folic acid
L-5-methyltetrahydrofolate
non-covalent interactions
stability
degradation pathway
title Comparison of Interactions Between Soy Protein Isolate and Three Folate Molecules: Effect on the Stabilization, Degradation, and Oxidization of Folates and Protein
title_full Comparison of Interactions Between Soy Protein Isolate and Three Folate Molecules: Effect on the Stabilization, Degradation, and Oxidization of Folates and Protein
title_fullStr Comparison of Interactions Between Soy Protein Isolate and Three Folate Molecules: Effect on the Stabilization, Degradation, and Oxidization of Folates and Protein
title_full_unstemmed Comparison of Interactions Between Soy Protein Isolate and Three Folate Molecules: Effect on the Stabilization, Degradation, and Oxidization of Folates and Protein
title_short Comparison of Interactions Between Soy Protein Isolate and Three Folate Molecules: Effect on the Stabilization, Degradation, and Oxidization of Folates and Protein
title_sort comparison of interactions between soy protein isolate and three folate molecules effect on the stabilization degradation and oxidization of folates and protein
topic soy protein
folic acid
L-5-methyltetrahydrofolate
non-covalent interactions
stability
degradation pathway
url https://www.mdpi.com/2304-8158/13/24/4033
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