成熟过程中活性氧簇（ROS）对肌原纤维蛋白结构的影响

Effect of Reactive Oxygen Species (ROS) on Structural Changes in Meat Myofibrillar Protein during Ageing

摘要:

以拉曼光谱为主要技术手段，观测了鹅肉成熟过程中，肌原纤维蛋白在ROS诱导剂双氧水（H2O2）与ROS清除剂N-乙酰半胱氨酸（NAC）的对照处理下，其主链构象及氨基酸残基微环境的变化。经10 mmol H2O2处理后的鹅肉组织中，ROS的相对含量明显高于10 mmol NAC处理组（p<0.05）。伴随着ROS含量的升高，H2O2处理组α-螺旋的含量显著下降（p<0.05），β-折叠的含量显著上升（p<0.05）；而在NAC处理组，α-螺旋的含量显著下降（p<0.05），无规则卷曲显著上升（p<0.05）；蛋白质二级结构的变化，特别是α-螺旋与β-折叠之间的转化与蛋白质的凝胶特性密切相关。H2O2处理组骨架C-C、C-N的伸缩振动强度下降幅度明显高于NAC处理组，说明ROS攻击骨架肽链使蛋白发生降解；H2O2处理组760 cm-1的归一化强度的下降趋势也明显高于NAC处理组，表明氧化增强了蛋白质的表面疏水性。

Abstract:

In this study, Raman spectroscopy was used to analyze changes in the main chain of myofibrillar protein and the microenvironment of amino acid residues in goose meat while ageing. The observations were conducted in a controlled experiment using the ROS inducer, hydrogen peroxide (H2O2), and N-acetyl cysteine (NAC), a ROS scavenger. After treatment with10 mmol H2O2 solution for 96 h, the relative content of ROS in goose muscle tissues was visibly higher than that in the NAC group (p<0.05). With increasing ROS concentration, the α-helix content decreased significantly (p<0.05), where as the β-sheet content increased significantly (p<0.05) in the H2O2 group. While in the NAC group, the α-helix content decreased significantly (p<0.05), but the content of random coils increased significantly (p<0.05). Changes in secondary protein structure, especially the transformation between α-helix and β-sheet forms, are closely related to gelling properties of the protein. The decline in intensity of C-C\C-N skeletal stretching vibrations was greater in the H2O2 group than in the NAC group, indicating that ROS could target the skeletal peptide bond and induce protein degradation. The normalized decline in intensity of the Raman band at 760 cm-1 was more pronounced in the H2O2 group than in the NAC group, suggesting that oxidation could enhance the surface hydrophobicity of proteins.