Novel Angiotensin-Converting Enzyme-Inhibitory Peptides From Fermented Bovine Milk Started by Lactobacillus helveticus KLDS.31 and Lactobacillus casei KLDS.105: Purification, Identification, and Interaction Mechanisms

Jiaqi Li; Jiajia Zhao; Xindi Wang; Abdul Qayum; Muhammad Altaf Hussain; Guizhao Liang; Juncai Hou; Zhanmei Jiang; Aili Li

doi:10.3389/fmicb.2019.02643

Novel Angiotensin-Converting Enzyme-Inhibitory Peptides From Fermented Bovine Milk Started by Lactobacillus helveticus KLDS.31 and Lactobacillus casei KLDS.105: Purification, Identification, and Interaction Mechanisms

Front Microbiol. 2019 Nov 28:10:2643. doi: 10.3389/fmicb.2019.02643. eCollection 2019.

Authors

Jiaqi Li¹, Jiajia Zhao¹, Xindi Wang¹, Abdul Qayum¹, Muhammad Altaf Hussain¹, Guizhao Liang², Juncai Hou¹, Zhanmei Jiang¹, Aili Li¹

Affiliations

¹ Key Laboratory of Dairy Science, Ministry of Education, Food Science College, Northeast Agricultural University, Harbin, China.
² Bioengineering College, Chongqing University, Chongqing, China.

Abstract

Fermented milks with strong angiotensin I-converting enzyme (ACE)-inhibitory activity were obtained through a culture with Lactobacillus helveticus KLDS.31 and Lactobacillus casei KLDS.105 with a fermentation and storage temperature of 37 °C. Ultrafiltration fractions with a molecular weight less than 3 kDa in fermented milk whey exhibited the strongest inhibitory activity. Correspondingly, a gastrointestinal digestion experiment showed retention of the bioactivity of these fractions with pepsin and trypsin treatment. Four ACE-inhibitory peptides from fermented milk were isolated, purified by two-step reverse chromatography, and sequenced. Furthermore, the interaction mechanisms between ACE and four isolated peptides were investigated by a molecular docking method and the Independent Gradient Model. Experimental determination of IC₅₀ was done to verify theoretical results. The inhibitory peptide interacted with ACE as follows: Lys-Pro-Ala-Gly-Asp-Phe > Lys-Ala-Ala-Leu-Ser-Gly-Met > Lys-Lys-Ala-Ala-Met-Ala-Met > Leu-Asp-His-Val-Pro-Gly-Gly-Ala-Arg.

Keywords: angiotensin-converting enzyme inhibitory peptides; fermented bovine milk; isolation; molecular interaction; sequence identification.