Ding Xiuzhen, Hua Yufei, Chen Yeming, Zhang Caimeng, Kong Xiangzhen
State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
Int J Mol Sci. 2015 Apr 10;16(4):8040-58. doi: 10.3390/ijms16048040.
Many thiol-containing molecules show heavy metal complexation ability and are used as antidotes. In this study, the potential function associated with thiol-containing peptides (TCPs) from soy protein hydrolysates as natural detoxicants for heavy metals is reported. TCPs enriched by Thiopropyl-Sepharose 6B covalent chromatography had different molecular weight distributions as well as different numbers of proton dissociable groups, depending on the proteases and degree of hydrolysis. The major contribution of sulfhydryl groups was confirmed by the largest pH decrease between 8.0 and 8.5 of the pH titration curves. The complexation of TCPs with heavy metals was evaluated by stability constants (βn) of TCP-metal complexes whose stoichiometry was found to be 1:1 (ML) and 1:2 (ML2). TCPs from degree of hydrolysis of 25% hydrolysates gave high affinities towards Hg2+, Cd2+, and Pb2+ (giving similar or even bigger lgβ values than that of glutathione). A significantly positive correlation was found between the logarithm of stability constants for ML2 (lgβ2) and the sulfhydryl group content. Molecular weight distribution of TCPs affected the complexation with Pb2+ notably more than Hg2+ and Cd2+. These results suggest that soy TCPs have the potential to be used in the formulation of functional foods to counteract heavy metal accumulation in humans.
许多含硫醇的分子具有重金属络合能力，并被用作解毒剂。在本研究中，报道了大豆蛋白水解物中含硫醇肽（TCPs）作为重金属天然解毒剂的潜在功能。通过硫丙基-琼脂糖6B共价色谱法富集的TCPs具有不同的分子量分布以及不同数量的质子可解离基团，这取决于蛋白酶和水解程度。巯基的主要贡献通过pH滴定曲线在8.0至8.5之间最大的pH下降得到证实。通过TCP-金属络合物的稳定常数（βn）评估TCPs与重金属的络合，发现其化学计量比为1:1（ML）和1:2（ML2）。水解度为25%的水解物中的TCPs对Hg2+、Cd2+和Pb2+具有高亲和力（给出的lgβ值与谷胱甘肽相似甚至更大）。发现ML2的稳定常数对数（lgβ2）与巯基含量之间存在显著正相关。TCPs的分子量分布对与Pb2+的络合影响明显大于对Hg2+和Cd2+的影响。这些结果表明，大豆TCPs有潜力用于功能性食品配方中，以对抗人体中的重金属积累。
