Udenigwe Chibuike C, Wu Sihong, Drummond Kiesha, Gong Min
Health and Bioproducts Research Laboratory, Department of Environmental Sciences, Faculty of Agriculture, Dalhousie University , Truro, Nova Scotia B2N 5E3, Canada.
J Agric Food Chem. 2014 Jan 8;62(1):130-5. doi: 10.1021/jf403405r. Epub 2013 Dec 20.
Plastein, a product of protease-induced peptide aggregation, is thought to possess unique physical properties and bioactivity, although its formation, stability, and functional mechanisms remain unclear. This study demonstrates that plastein is formed from bovine casein peptides with Alcalase by hydrophobic and electrostatic interactions and less likely by covalent bonding. The peptide aggregation enhanced the Fe(III) reducing potential and decreased the Fe(II) chelating activity (p < 0.05) of casein peptides, but there was no difference in inhibition of Fe-induced linoleic acid peroxidation after plastein reaction. The casein plastein product retained its antioxidative activities after being heated at 100 °C. However, simulated gastric protease treatment with pepsin and pancreatic enzymes resulted in enhanced reducing potential and metal chelation of the casein plastein and reduction of the inhibitory effect on lipid peroxidation. It appears that the plasteins were disintegrated and further hydrolyzed by gastric proteases on the basis of the antioxidative capacity and RP-HPLC profile being similar to those of the casein hydrolysates. Therefore, plastein reaction may not confer metabolic stability or enhance the antioxidative capacity of casein peptides for prospective functional food applications.
类蛋白是蛋白酶诱导肽聚集的产物，尽管其形成、稳定性和功能机制尚不清楚，但人们认为它具有独特的物理性质和生物活性。本研究表明，类蛋白是由碱性蛋白酶作用于牛乳酪蛋白肽通过疏水作用和静电相互作用形成的，而非通过共价键形成。肽聚集增强了酪蛋白肽的铁（III）还原能力，降低了其铁（II）螯合活性（p < 0.05），但类蛋白反应后对铁诱导的亚油酸过氧化的抑制作用没有差异。酪蛋白类蛋白产物在100℃加热后仍保留其抗氧化活性。然而，用胃蛋白酶和胰酶进行模拟胃蛋白酶处理后，酪蛋白类蛋白的还原能力和金属螯合能力增强，对脂质过氧化的抑制作用降低。基于抗氧化能力和反相高效液相色谱图谱与酪蛋白水解产物相似，似乎类蛋白被胃蛋白酶分解并进一步水解。因此，对于预期用于功能性食品的应用，类蛋白反应可能不会赋予酪蛋白肽代谢稳定性或增强其抗氧化能力。
