Wang Rongxin, Ye Meijun, Zhu Suyin, Zeng Qingzhu, Yuan Yang
School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou, China.
Front Nutr. 2023 Jul 6;10:1211609. doi: 10.3389/fnut.2023.1211609. eCollection 2023.
Zinc is an essential trace element for the human body. Recently, a novel Zn-binding peptide, Lys-Tyr-Lys-Arg-Gln-Arg-Trp (PP), was purified and identified from soy protein hydrolysates with high Zn-binding capacity (83.21 ± 2.65%) by our previous study. The preparation of soy meal hydrolysates (SMHs)-Zn complexes is convenient and low-cost, while PP (Lys-Tyr-Lys-Arg-Gln-Arg-Trp)-Zn complexes have a higher coordination rate but a relatively high cost. The aim of this study was to investigate the effect of soy meal hydrolysates (SMHs)-Zn complexes on zinc absorption in mice model, and synthetic soy peptide (PP)-Zn complexes with high Zn-binding capacity were used as control. Firstly, SMHs were prepared by enzymolysis, and the PP (Lys-Tyr-Lys-Arg-Gln-Arg-Trp) were synthesized based on previous studies. The binding mechanism of soy hydrolysates and zinc was analyzed by spectral analysis. Furthermore, the cytotoxicity of the SMHs-Zn complexes was also studied using the CCK-8 method. The effect of zinc absorption was evaluated based on Zn content, total protein and albumin content, relevant enzyme system, and the PeT1 and ZnT1 mRNA expression levels.
The result showed that zinc was bound with carboxyl oxygen and amino nitrogen atoms on SMHs, with hydrophobic and electrostatic interactions as auxiliary stabilizing forces. SMHs-Zn were proved to have great solubility and a small particle size at different pH values, and it showed a beneficial effect on Caco-2 cells growth. Moreover, it was proved that SMHs-Zn and PP-Zn could increase the levels of zinc and the activity of Zn-related enzymes in mice. SMHs-Zn possessed higher PepT1 and ZnT1 mRNA expression levels than PP-Zn in the small intestine.
SMHs-Zn with a lower Zn-binding capacity had similar effects on zinc absorption in mice as PP-Zn, suggesting that the bioavailability of peptide-zinc complexes in mice was not completely dependent on their Zn-binding capacity, but may also be related to the amino acid composition.
锌是人体必需的微量元素。最近，通过我们之前的研究，从具有高锌结合能力（83.21±2.65%）的大豆蛋白水解物中纯化并鉴定出一种新型锌结合肽，即赖氨酸-酪氨酸-赖氨酸-精氨酸-谷氨酰胺-精氨酸-色氨酸（PP）。豆粕水解物（SMHs）-锌复合物的制备方便且成本低，而PP（赖氨酸-酪氨酸-赖氨酸-精氨酸-谷氨酰胺-精氨酸-色氨酸）-锌复合物具有较高的配位率，但成本相对较高。本研究的目的是在小鼠模型中研究豆粕水解物（SMHs）-锌复合物对锌吸收的影响，并以具有高锌结合能力的合成大豆肽（PP）-锌复合物作为对照。首先，通过酶解制备SMHs，并根据之前的研究合成PP（赖氨酸-酪氨酸-赖氨酸-精氨酸-谷氨酰胺-精氨酸-色氨酸）。通过光谱分析分析大豆水解物与锌的结合机制。此外，还使用CCK-8法研究了SMHs-锌复合物的细胞毒性。基于锌含量、总蛋白和白蛋白含量、相关酶系统以及PeT1和ZnT1 mRNA表达水平评估锌吸收的效果。
结果表明，锌与SMHs上的羧基氧和氨基氮原子结合，疏水和静电相互作用作为辅助稳定力。事实证明，SMHs-锌在不同pH值下具有良好的溶解性和小粒径，并且对Caco-2细胞生长显示出有益作用。此外，已证明SMHs-锌和PP-锌可提高小鼠体内锌的水平和锌相关酶的活性。在小肠中，SMHs-锌的PepT1和ZnT1 mRNA表达水平高于PP-锌。
具有较低锌结合能力的SMHs-锌对小鼠锌吸收的影响与PP-锌相似，这表明小鼠体内肽-锌复合物的生物利用度并不完全取决于它们的锌结合能力，还可能与氨基酸组成有关。
