镉超标籼米麸皮中金属硫蛋白微观结构表征

The microstructural characterization of metallothionein from cadmium long-shaped rice bran

以镉超标籼米为原料,将其打磨取麸皮提取金属硫蛋白(Metallothionein,MT),研究其紫外吸光、二级结构、氨基酸组成等微观结构性质。结果表明,MT在291 nm处有最大吸收峰;二级结构组成为α-螺旋26.1%、β-折叠18.7%,β-转角22.6%,无规卷曲32.6%;MT氨基酸组成与原料相比,甲硫氨酸、半胱氨酸等含硫氨基酸含量增高,酪氨酸、苯丙氨酸等芳香族氨基酸含量减少;与镉结合蛋白(Cd-binding protein,CBP)相比各种氨基酸含量均有减少;扫描电子显微镜(Scanning electron microscope,SEM)显示MT微观形态结构呈多孔状,有明显圆球状末端。

The UV absorbance, protein secondary structure, amino acid composition and microstructure of metallothionein from cadmium long-shaped rice bran were investigated. Results showed that the absorption peak of MT is 291 nm. Protein secondary structure composed of 26.1% alpha helix, 18.7%beta fold, 22.6% beta angle, 32.6% random coil. Metallothionein amino acid composition compared to raw materials, sulfur-containing amino acid such as methionine and cysteine contents were increased,aromatic amino acids such as tyrosine and phenylalanine were reduced. Compared with Cd-binding protein, all kinds of amino acid contents were reduced. Scanning electron microscope(SEM) show that the microstructure of MT is porous and has significant bulbous termination.