Department of Life Sciences, University of Limerick, Ireland.
Department of Life Sciences, University of Limerick, Ireland; Food for Health Ireland, University of Limerick, Ireland.
Food Chem. 2014 Aug 1;156:29-36. doi: 10.1016/j.foodchem.2014.01.056. Epub 2014 Jan 27.
The hydrolytic specificity of Aspergillus niger prolyl endoproteinase (An-PEP) on purified β-casein (β-CN) was assessed. This analysis confirmed cleavage at the C-terminal side of Pro residues. An-PEP also had the ability to cleave at the C-terminal side of Ala, Glu, Gly, Ser, Lys and Leu. Incubation of purified β-CN with An-PEP resulted in the generation of highly potent angiotensin converting enzyme (ACE) inhibitory hydrolysates. The most potent hydrolysate was obtained after 24h incubation (ACE IC50=16.41±6.06μg/mL). Fourteen β-CN derived C-terminal Pro-containing di-, tri, and tetrapeptides which were predicted in silico to be released following An-PEP hydrolysis or which were detected by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS) in the 24h hydrolysate were synthesised and characterised for their ACE inhibitory activity. The most potent inhibitory peptides were Ile-Gln-Ala (β-CN f187-189) and Val-Glu-Pro (β-CN f116-118) having ACE IC50 values of 32.9±9.2 and 63.7±12.0μM, respectively. The hydrolysates generated appear to have the most potent ACE IC50 values reported for a food derived hydrolysate to date.
黑曲霉脯氨酸内切蛋白酶（An-PEP）对纯化的β-酪蛋白（β-CN）的水解特异性进行了评估。该分析证实了脯氨酸残基的 C 末端侧的切割。An-PEP 还能够在丙氨酸、谷氨酸、甘氨酸、丝氨酸、赖氨酸和亮氨酸的 C 末端侧切割。用 An-PEP 孵育纯化的β-CN 会产生具有高血管紧张素转化酶（ACE）抑制活性的水解产物。孵育 24 小时后得到的水解产物具有最强的抑制活性（ACE IC50=16.41±6.06μg/mL）。通过计算机预测，在 An-PEP 水解后会释放出 14 种β-CN 衍生的 C 末端含有脯氨酸的二肽、三肽和四肽，或者通过超高效液相色谱-质谱联用（UPLC-MS/MS）在 24 小时的水解产物中检测到这些肽，这些肽都被合成并对其 ACE 抑制活性进行了表征。最有效的抑制肽是 Ile-Gln-Ala（β-CN f187-189）和 Val-Glu-Pro（β-CN f116-118），它们的 ACE IC50 值分别为 32.9±9.2 和 63.7±12.0μM。生成的水解产物似乎具有迄今为止报道的源自食物的水解产物中最强的 ACE IC50 值。
