Department of Nutrition, Food Science and Packaging , California State University , San Jose , California 95192 , United States.
Research Institute of Agricultural Products Processing and Nuclear-Agricultural Technology , Hubei Academy of Agricultural Sciences , Wuhan , Hubei 430064 , China.
J Agric Food Chem. 2019 Jan 30;67(4):1261-1268. doi: 10.1021/acs.jafc.8b05924. Epub 2019 Jan 16.
Many organisms possess the ability to produce metal-binding proteins to absorb cadmium. Metallothioneins, an important family of cysteine-rich metal-binding proteins, have been isolated and well characterized. However, Lentinula edodes may have a different type of cadmium-binding protein that contains fewer cysteine residues. In the present study, we purified a cadmium-binding protein from L. edodes (LECBP) by gel filtration and anion exchange chromatography and then identified LECBP by LC-MS/MS. We found LECBP to be a novel cadmium-binding protein, which contained 220 amino acid residues but no cysteine residue. LECBP had a high binding affinity for Cd(II) with a K value of 97.3 μM. The percentages of α-helix, β-sheet, β-turn, and random coil in LECBP were 15.7%, 39.4%, 8.0%, and 37.1%, respectively. In addition, high temperatures and an acidic environment influenced the conformation of LECBP. Our results will thus provide a new perspective to understand the mechanism of cadmium accumulation in L. edodes.
许多生物体都具有产生金属结合蛋白来吸收镉的能力。金属硫蛋白是一类富含半胱氨酸的重要金属结合蛋白，已经被分离并得到很好的表征。然而，香菇可能有一种不同类型的镉结合蛋白，它含有较少的半胱氨酸残基。在本研究中，我们通过凝胶过滤和阴离子交换层析从香菇中纯化了一种镉结合蛋白（LECBP），然后通过 LC-MS/MS 鉴定了 LECBP。我们发现 LECBP 是一种新型的镉结合蛋白，它含有 220 个氨基酸残基，但没有半胱氨酸残基。LECBP 对 Cd(II)具有高的结合亲和力，K 值为 97.3 μM。LECBP 中的α-螺旋、β-折叠、β-转角和无规则卷曲的比例分别为 15.7%、39.4%、8.0%和 37.1%。此外，高温和酸性环境会影响 LECBP 的构象。因此，我们的研究结果将为理解香菇中镉积累的机制提供新的视角。
