Isolation and characterization of antihypertensive peptides from soy bean protein

Proteins and peptides are the most diverse biomolecules found in nature and make our interest due to their wide applications in food and pharmaceutical industry. Angiotensin Converting Enzyme (ACE) plays a major role in controlling blood pressure. The inhibition of ACE with peptides is a main target in the regulation of hypertension. The objective of the present study was to investigate the therapeutic potential of soy bean. This was accomplished by isolation of ACE inhibitory peptides using response surface methodology (RSM) and characterization of these bioactive peptides by mass spectrometry. 31 hydrolyzed fractions were isolated and evaluated for their ACE inhibition potential. Hydrolyzed fraction having highest ACE inhibitory activity was characterized by liquid chromatography-mass spectrometry (LC-MS) technique. RSM results showed maximum ACE inhibition potential (64%) by hydrolyzate was obtained at 45 ºC temperature, pH 8.0, E/S 0.2 in 2 hours hydrolysis time. Results of LC-MS analysis revealed Ser-Gly, Ser-Pro, Met-Ala, His-Ala, Lys-Pro, Phe-Thr, Met-Leu, Pro-Arg, Ala-Pro-Val, Pro-Ala-Leu, Val-Met-Gly, Pro-Leu-Val, Pro-Pro-Gln, His-Arg-Gly, Ser-Phe-Val-Leu, Ala-Val-His-Try, Arg-Thr-Val-Arg, His-His-Tyr-Leu-Val, Asp-Gly-Ala-Cys-Ser-Ala-Asn and MetVal-Thr-Gly-Pro-Gly-Cys-His bioactive peptides in hydrolyzed fraction of soy bean. Our data provide evidence that response surface methodology is a good approach for isolation of antihypertensive bioactive peptides with more potent activity as nutraceuticals or pharmaceuticals. Therefore soy bean can be use for industrial production of pharmaceutical grade natural medicines for handling high blood pressure.

The insertion of bioactive peptides at the C-terminal end of an 11S globulin changes the structural stability and improves the antihypertensive activity

BACKGROUND: The 11S globulin from amaranth is the most abundant storage protein in mature seeds and is well recognized for its nutritional value. We used this globulin to engineer a new protein by adding a four valinetyrosine antihypertensive peptide at its C-terminal end to improve its functionality. The new protein was named AMR5 and expressed in the Escherichia coli BL21-CodonPlus(DE3)-RIL strain using a custom medium (F8PW) designed for this work. RESULTS: The alternative medium allowed for the production of 652 mg/L expressed protein at the flask level, mostly in an insoluble form, and this protein was subjected to in vitro refolding. The spectrometric analysis suggests that the protein adopts a ß/α structure with a small increment of α-helix conformation relative to the native amaranth 11S globulin. Thermal and urea denaturation experiments determined apparent Tm and C1/2 values of 50.4°C and 3.04 M, respectively, thus indicating that the antihypertensive peptide insertion destabilized the modified protein relative to the native one. AMR5 hydrolyzed by trypsin and chymotrypsin showed 14- and 1.3-fold stronger inhibitory activity against angiotensin I-converting enzyme (IC50 of 0.034 mg/mL) than the unmodified protein and the previously reported amaranth acidic subunit modified with antihypertensive peptides, respectively. CONCLUSION: The inserted peptide decreases the structural stability of amaranth 11S globulin and improves its antihypertensive activity.

ABSORPTION MECHANISM OF THE ANTIHYPERTENSIVE PEPTIDE VAL-LEU-PRO-VAL-PRO IN CACO-2 CELL MODEL / 营养学报

Objective To study the absorption mechanism of the antihypertensive peptide,Val-Leu-Pro-Pro-Val(VLPVP) in Caco-2 cell model. Method Caco-2 cell model was used in vitro to investigate the effects of time,pH,drug concentration,enhancers and inhibitors on the absorption of VLPVP. VLPVP concentration was measured by HPLC. Results The transport rate of VLPVP reached the maximal level at pH7.4,and was positively correlated to transport time and drug concentration. The peptide transporter inhibitors(Gly-Pro,arphamenine A) ,the endocytosis inhibitor(phenyl arsenoxide) didn’t influence the transport of VLPVP,while the paracellular transport enhancer(sodium deoxycholate) ,the inhibitor of multi-drug resistant protein(MK-571) and the energy inhibitor(sodium azide) enhanced it from apical to basolateral side significantly,but the latter two didn’t influence the transport from basolateral to apical side. Conclusion Paracellular diffusion was suggested to have been the main mechanism for the absorption of intact VLPVP and MRP2 had strong eflux effect on the transepithelial transport of VLPVP.