Detection of an angiotensin converting enzyme inhibitory peptide from peanut protein isolate and peanut polypeptides by western blot and dot blot hybridization

Potential of Marine Bacterial Metalloprotease A69 in the Preparation of Peanut Peptides with Angiotensin-Converting Enzyme (ACE)-Inhibitory and Antioxidant Properties

Marine bacterial proteases have rarely been used to produce bioactive peptides, although many have been reported. This study aims to evaluate the potential of the marine bacterial metalloprotease A69 from recombinant Bacillus subtilis in the preparation of peanut peptides (PPs) with antioxidant activity and angiotensin-converting enzyme (ACE)-inhibitory activity. Based on the optimization of the hydrolysis parameters of protease A69, a process for PPs preparation was set up in which the peanut protein was hydrolyzed by A69 at 3000 U g-1 and 60 °C, pH 7.0 for 4 h. The prepared PPs exhibited a high content of peptides with molecular weights lower than 1000 Da (>80%) and 3000 Da (>95%) and contained 17 kinds of amino acids. Moreover, the PPs displayed elevated scavenging of hydroxyl radical and 1,1-diphenyl-2-picryl-hydrazyl radical, with IC50 values of 1.50 mg mL-1 and 1.66 mg mL-1, respectively, indicating the good antioxidant activity of the PPs. The PPs also showed remarkable ACE-inhibitory activity, with an IC50 value of 0.71 mg mL-1. By liquid chromatography mass spectrometry analysis, the sequences of 19 ACE inhibitory peptides and 15 antioxidant peptides were identified from the PPs. These results indicate that the prepared PPs have a good nutritional value, as well as good antioxidant and antihypertensive effects, and that the marine bacterial metalloprotease A69 has promising potential in relation to the preparation of bioactive peptides from peanut protein.

Recent Research in Antihypertensive Activity of Food Protein-derived Hydrolyzates and Peptides

Year to year obesity prevalence, reduced physical activities, bad habits/or stressful lifestyle, and other environmental and physiological impacts lead to increase in diseases such as coronary heart disease, stroke, cancer, diabetes, and hypertension worldwide. Hypertension is considered as one of the most common serious chronic diseases; however, discovery of medications with high efficacy and without side effects for treatment of patients remains a challenge for scientists. Recent trends in functional foods have evidenced that food bioactive proteins play a major role in the concepts of illness and curing; therefore, nutritionists, biomedical scientists, and food scientists are working together to develop improved systems for the discovery of peptides with increased potency and therapeutic benefits. This review presents a recent research carried out to date for the purpose of isolation and identification of bioactive hydrolyzates and peptides with angiotensin I converting enzyme inhibitory activity and antihypertensive effect from animal, marine, microbial, and plant food proteins. Effects of food processing and hydrolyzation conditions as well as some other impacts on formation, activity, and stability of these hydrolyzates and peptides are also presented.

An endurance-enhancing effect of peanut meal protein hydrolysate in mice: possible involvement of a specific peanut peptide

To improve the functional properties of peanut meal protein for wide utilization, hydrolysis was conducted by alcalase. Compared with saline and peanut meal protein, intragastric administration of low molecular weight (<1 kD) peanut meal peptide (PPH I) could significantly prolong swimming time, increase levels of blood sugar, non-esterified fatty acids (NEFA) and liver glycogen and decrease blood lactate content in mice. Levels of Pro, Leu, Val and His in low molecular weight peanut meal peptides were higher significantly than those in other peanut meal protein hydrolysates. Hydrophobic amino acids, such as Pro, Tyr and His, could perhaps capture free radical and increase antioxidant capacity of peanut peptide and retard fatigue induced by free radical. After separation by HPLC, a primary peptide P1, Pro-Glu-Ile-Glu-Val, was sequenced. Its N-terminal was Val, and it was rich in antioxidant amino acid, Pro and Ile. Levels of plasma glucose, NEFA and liver glycogen in PPH I group were higher than those in mice intragastric administration with peptide P1, and the swimming time is longer in PPH I group than in P1 group. So, the high content of P1 was one of the reason why PPH I had high endurance-enhancing capacity.

Arachin derived peptides as selective angiotensin I-converting enzyme (ACE) inhibitors: structure-activity relationship

Current attention focuses on mechanisms of controlling blood pressure through the inhibition of angiotensin I-converting enzyme (ACE). Bioactive antihypertensive peptides of food origin are increasingly gaining importance as alternates to synthetic drugs in hypertension therapy. The ACE inhibitory property of an enzymatic digest of arachin, the major storage globulin of peanut (Arachis hypogaea) has been demonstrated. The ACE inhibitory activity of a tripeptide (IEY) isolated from these digests has been characterized. Five synthetic structural analogs of this peptide (IEW, IKY, IKW, IEP and IKP) were assembled and their ACE inhibitory activity evaluated. Among these, the tripeptide IKP was a potent competitive inhibitor with an IC(50) of 7+/-1 x 10(-6)M similar to that of the potent whey peptides IPP and VPP. The inhibition data of these peptide analogs have been rationalized through docking simulations using the tACE-lisinopril complex at 2A resolution (PDB: 1086). The best docking poses were located at the tACE catalytic site resembling the mode of inhibition exerted by lisinopril, the synthetic drug. The degree of inhibition by the peptides correlated with the coordination distance between the catalytic Zn(II) and the carbonyl oxygen of the peptide bond between the amino-terminal and middle residue. These studies illustrate that these peptides, like lisinopril, behave as transition state analog inhibitors and are useful in therapeutic intervention for blood pressure management.