Structural and conformational changes in models of β-lactoglobulin modified by Michael addition of 1,2-benzoquinones using molecular dynamics and metadynamics simulations

IF 11 1区农林科学 Q1 CHEMISTRY, APPLIED

Food Hydrocolloids Pub Date : 2025-05-30 DOI:10.1016/j.foodhyd.2025.111584

Khadija Waqar , Suk Kyu Ko , Helena Damtoft Tjørnelund , Karsten Olsen , Mahesha M. Poojary , Günther H.J. Peters , Marianne N. Lund

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引用次数: 0

Abstract

Food proteins react with o-quinones (oxidized polyphenols), and the resulting protein-polyphenol Michael adducts can alter the protein structure leading to changes in functional properties of food proteins. The present work investigated structural changes in models of protein-polyphenol Michael adducts (exemplified with β-lactoglobulin (β-LG) covalently modified with 4-methylcatechol (4MC), a model polyphenol similar to the B ring of flavonoids) using molecular dynamics (MD) and metadynamics (MTD) simulations. Based on experimentally identified 4MC modified sites in β-LG, β-LG-4MC model adducts (hereafter referred to as β-LQ) were designed with 19 site-specific 4MC modifications (β-LQ19) and with the four most abundant 4MC modifications (β-LQ4). The unliganded structure of β-LG was used as control. 4MC modifications in β-LQ model adducts compared with β-LG resulted in increased protein flexibility, however the tertiary structures remained unaffected by the modifications during 400 ns MD simulations. Both MD and MTD (with secondary structure as independent variable) data indicated that the α-helix structure was more susceptible to loss compared to the β-sheet structure in β-LQ model adducts, as opposed to β-LG. The metastable states determined with MTD simulations (with root mean squared deviations as independent variable) showed unfolding in thermally sensitive regions (amino acid residues 57 to 70) in β-LQ19. The structural changes (loss of α-helix and unfolding) exhibited by β-LQ19 explain the experimentally determined reduced denaturation temperature in β-LQ compared with β-LG.

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1,2-苯醌修饰β-乳球蛋白模型的分子动力学和元动力学模拟

食物蛋白质与邻醌（氧化多酚）发生反应，产生的蛋白质-多酚迈克尔加合物可以改变蛋白质结构，从而改变食物蛋白质的功能特性。本研究利用分子动力学（MD）和元动力学（MTD）模拟研究了蛋白质-多酚Michael加合物（以4-甲基儿茶酚（4MC）共价修饰的β-乳球蛋白（β-LG）为例，4-甲基儿茶酚是一种类似黄酮类化合物B环的模型多酚）的结构变化。根据实验确定的β-LG中4MC修饰位点，设计了具有19个位点特异性4MC修饰位点（β-LQ19）和4个最丰富的4MC修饰位点（β-LQ4）的β-LG-4MC模型加合物（以下简称β-LQ）。以β-LG的无配体结构为对照。与β-LG相比，β-LQ模型加合物中的4MC修饰增加了蛋白质的柔韧性，但在400 ns MD模拟过程中，三级结构没有受到修饰的影响。MD和MTD（二级结构为自变量）数据表明，β-LQ模型加合物中α-螺旋结构比β-薄片结构更容易损失，而β-LG模型加合物中α-螺旋结构比β-薄片结构更容易损失。用MTD模拟（以均方根偏差为自变量）确定的亚稳态显示在β-LQ19的热敏区（氨基酸残基57 ~ 70）展开。β-LQ19表现出的结构变化（α-螺旋的丢失和展开）解释了β-LQ与β-LG相比，实验测定的变性温度降低。

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来源期刊

Food Hydrocolloids 工程技术-食品科技

CiteScore

19.90

自引率

14.00%

发文量

871

审稿时长

37 days

期刊介绍： Food Hydrocolloids publishes original and innovative research focused on the characterization, functional properties, and applications of hydrocolloid materials used in food products. These hydrocolloids, defined as polysaccharides and proteins of commercial importance, are added to control aspects such as texture, stability, rheology, and sensory properties. The research's primary emphasis should be on the hydrocolloids themselves, with thorough descriptions of their source, nature, and physicochemical characteristics. Manuscripts are expected to clearly outline specific aims and objectives, include a fundamental discussion of research findings at the molecular level, and address the significance of the results. Studies on hydrocolloids in complex formulations should concentrate on their overall properties and mechanisms of action, while simple formulation development studies may not be considered for publication. The main areas of interest are: -Chemical and physicochemical characterisation Thermal properties including glass transitions and conformational changes- Rheological properties including viscosity, viscoelastic properties and gelation behaviour- The influence on organoleptic properties- Interfacial properties including stabilisation of dispersions, emulsions and foams- Film forming properties with application to edible films and active packaging- Encapsulation and controlled release of active compounds- The influence on health including their role as dietary fibre- Manipulation of hydrocolloid structure and functionality through chemical, biochemical and physical processes- New hydrocolloids and hydrocolloid sources of commercial potential. The Journal also publishes Review articles that provide an overview of the latest developments in topics of specific interest to researchers in this field of activity.