College of Food Science and Technology, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan 430070, PR China; Key Laboratory of Environment Correlative Dietology, Huazhong Agricultural University, Ministry of Education, Wuhan 430070, PR China.
College of Food Science and Technology, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan 430070, PR China.
Food Chem. 2015 May 1;174:291-8. doi: 10.1016/j.foodchem.2014.10.131. Epub 2014 Nov 13.
To examine the mechanisms in the interaction of sorghum procyanidins trimer (SPT) with porcine pancreatic α-amylase (PPA), fluorescence quenching, circular dichroism, and UV spectra methods were adopted. The procyanidins binding mode, binding constant and effect of procyanidins on protein stability and conformation were determined. The fluorescence spectroscopy results showed that the Stern-Volmer quenching constant K(SV) of SPT on PPA, bimolecular quenching constant k(q), and apparent static quenching constant K were 2639.5 M(-1), 2.6395 × 10(11) M(-1) s(-1), and 495.19 M(-1), respectively. In addition, binding constant KA and number of binding sites were 872.971 M(-1) and 1, respectively. Circular dichroism study revealed that PPA conformation was altered by SPT with a major reduction of β-sheet, increase of β-turn, minor change of random coil. UV spectra indicated that SPT influenced the micro-environment of aromatic amino acid residues in PPA. These findings directly elucidate the mechanisms of high molecular weight SPT in interaction with PPA.
为了研究高粱原花青素三聚体（SPT）与猪胰α-淀粉酶（PPA）相互作用的机制，采用荧光猝灭、圆二色性和紫外光谱法。确定了原花青素的结合模式、结合常数以及原花青素对蛋白质稳定性和构象的影响。荧光光谱结果表明，SPT 对 PPA 的 Stern-Volmer 猝灭常数 K(SV)、双分子猝灭常数 k(q)和表观静态猝灭常数 K 分别为 2639.5 M(-1)、2.6395×10(11) M(-1) s(-1)和 495.19 M(-1)。此外，结合常数 KA 和结合位点数分别为 872.971 M(-1)和 1。圆二色性研究表明，SPT 改变了 PPA 的构象，β-折叠减少，β-转角增加，无规卷曲略有变化。紫外光谱表明，SPT 影响了 PPA 中芳香族氨基酸残基的微环境。这些发现直接阐明了高分子量 SPT 与 PPA 相互作用的机制。
