Converting Enzyme Inhibitory Peptides Research Articles

Purification of angiotensin converting enzyme (ACE) inhibitory peptides and antihypertensive effect generated from Indonesian traditional fermented beef (Cangkuk)

Purification of angiotensin converting enzyme (ACE) inhibitory peptides and antihypertensive effect generated from Indonesian traditional fermented beef (Cangkuk)

STUDY OF ANGIOTENSIN-I CONVERTING ENZYME INHIBITORY PEPTIDES DERIVED FROM Ficus pumila var. awkeotsang SEEDS HYDROLYSATE

Hypertension also known as high blood pressure that has associated with multi-metabolic pathways such as the renin-angiotensin-aldosterone system (RAAS). There have been several synthetic ACE inhibitory drugs used clinically as therapeutics for hypertension. However, synthetic drugs showed side effects on human health after long-term use. Therefore, alternative natural ACE inhibitors from food-derived are necessary to develop. The study aimed to examine the activity of angiotensin-I converting enzyme inhibitory peptides derived from Ficus pumila var. awkeotsang seeds hydrolysate and to study the efficiency of enzymatic digestion. This study used four enzymes (trypsin, pepsin, thermolysin, and chymotrypsin) to release bioactive peptides from Ficus pumila var. awkeotsang seeds that could exhibit an antihypertensive effect. The results showed that Ficus pumila var. awkeotsang trypsin hydrolysate has the highest ACEI activity, 90.37%, and the IC50 reached 169±3.5 µg/mL. Then, the hydrolysate produced by trypsin has the highest degree of hydrolysis, 4%, after 8 hours of incubation. Hence, Ficus pumila var. awkeotsang seeds hydrolysate could develop as an alternative natural product that is responsible for ACE-inhibitory activity.

Impact of Lactiplantibacillus plantarum and casein fortification on angiotensin converting enzyme inhibitory peptides in yogurt: identification and in silico analysis.

In this study, the effects of Lactiplantibacillus plantarum M11 (Lb. plantarum M11) in conjunction with sodium caseinate on the characteristics and angiotensin converting enzyme (ACE) inhibitory activity of yogurt were investigated. ACE inhibitory peptides (ACEIPs) in yogurt were identified by nano-LC-MS/MS and potential ACEIPs were predicted by in silico and molecular docking methods. The results showed that the ACE-inhibitory activity of yogurt was significantly enhanced (p < 0.05), while maintaining the quality characteristics of the yogurt. Thirteen ACEIPs in the improved yogurt (883 + M11-CS group) were identified, which were more abundant than the other yogurt groups (control 883 group, 883 + M11 group and 883-CS group). Two novel peptides with potential ACE inhibitory activity, YPFPGPIH and NILRFF, were screened. The two peptides showed PeptideRanker scores above 0.8, small molecular weight and strong hydrophobicity, and were non-toxic after prediction. Molecular docking results showed that binding energies with ACE were -9.4 kcal mol-1 and -10.7 kcal mol-1, respectively, and could bind to the active site of ACE. These results indicated that yogurt with Lb. plantarum M11 and sodium caseinate has the potential to be utilized as a functional food with antihypertensive properties. The combination of ACEIP-producing strains and casein fortification could be an effective method to promote the release of ACEIPs from yogurt.

In Vitro Stability of ACE-Inhibitory Peptides of Rohu Fish Waste to Heat, pH and Gastrointestinal Enzymes

Angiotensin-I converting enzyme inhibitory (ACEi) peptides were prepared from rohu (Labeo rohita) fish wastes by enzymatic hydrolysis [1.1% alcalase concentration (v/w); 130 min time; 52°C temperature and 0.8:1 solid-liquid ratio]. Ultrasound Assisted Enzymatic Extraction (UAEE) and Microwave Assisted Enzymatic Extraction (MAEE) were performed to enhance degree of hydrolysis (DH), ACEi activity, and peptide yield (PY). The ACEi peptides were examined for stability during thermal processing, varied pH treatments and in vitro gastrointestinal digestion. Peptides were stable at different temperatures (25, 37, 55, 75, and 100°C) except at 121°C which reduced their stability by 7%, 6.9% and 2.2% in UAEE, MAEE and Non-Assisted Enzymatic Extraction (NAEE) peptides, respectively. Similarly, peptides retained ACEi at pH 2 to 8 and subsequent reduction at pH&gt;8. In vitro digestion studies showed stability of all peptides to GI digestion at 0.05% pepsin, 0.05% trypsin, 0.05% chymotrypsin and the combination of 0.025% trypsin and 0.025% chymotrypsin except MAEE peptides showing less stability with pepsin (0.05%). Therefore, it is concluded that these ACEi peptides derived from rohu fish waste, stable to heat, pH and gastrointestinal enzymatic action, can be used as ingredient in functional foods, which undergo thermal processing and digestion.

Characterization of novel angiotensin-I converting enzyme inhibitory peptides derived from Taiwan red quinoa (Chenopodium formosanum Koidz.) seed proteins using two sequential bioassay-guided fractionations

Characterization of novel angiotensin-I converting enzyme inhibitory peptides derived from Taiwan red quinoa (Chenopodium formosanum Koidz.) seed proteins using two sequential bioassay-guided fractionations

Study of screening, transport pathway, and vasodilation mechanisms on angiotensin-I converting enzyme inhibitory peptide from Ulva prolifera proteins

Study of screening, transport pathway, and vasodilation mechanisms on angiotensin-I converting enzyme inhibitory peptide from Ulva prolifera proteins

Screening, Characterization, and Mechanistic Evaluation of Angiotensin Converting Enzyme Inhibitory Peptides Derived from Milk Fermented with Lactobacillus delbrueckii QS306 with and without Ultrahigh-Pressure Treatment.

In this study, the peptides in milk fermented with Lactobacillus delbrueckii QS306 with and without ultrahigh-pressure treatment were identified using UPLC-Q-exactive-HF-X-MS/MS. In total, 27 novel pentapeptides with potential angiotensin converting enzyme inhibitory (ACEI) activity were screened via bioinformatic analysis, and the activities of seven novel pentapeptides were assessed. Among them, HLPLP, PYPQR, and VAPFP exhibited better IC50 values. Stability assessment via in vitro simulation revealed that the three pentapeptides were significantly reduced (P < 0.05) during digestion but exhibited 85% activity after digestion. HLPLP was a competitive inhibitor, while PYPQR and VAPFP were noncompetitive inhibitors of ACE. Molecular docking indicated that the three peptides could stably bind to ACE. Molecular dynamics (MD) simulation and activity verification indicated that PYPQR and VAPFP had better stability and activity. This study demonstrated that novel ACEI pentapeptides in milk fermented with L. delbrueckii QS306 with and without ultrahigh-pressure treatment could be considered promising candidates for controlling hypertension.

Identification of novel angiotensin converting enzyme (ACE) inhibitory peptides from Pacific saury: In vivo antihypertensive effect and transport route

Nature food-derived angiotensin converting enzyme inhibitory peptides (ACEIPs) can be potent and safe therapeutics for many medical illnesses, particularly hypertension. In this study, novel ACEIPs were screened and identified from Pacific saury by bio-activity guided approach through ultrafiltration membrane, Sephadex G-25 and RP-HPLC. The antihypertensive effect of ultrafiltration fraction was confirmed with spontaneous hypertensive rats' (SHRs) model. The peptides sequences of which gave the best activity was identified by Q-Orbitrap-MS/MS and selectively synthesized based on the binding energy of molecular docking. Five peptides VVLASLK, LTLK, LEPWR, ELPPK and LPTEK were synthesized, and the peptide LEPWR (IC50 = 99.5 μM) showed the best ACE inhibitory ability. Furthermore, LEPWR against ACE in a mixed competitive pattern and formed six hydrogen bonds with ACE. Additionally, the apparent permeability coefficient (Papp) of LEPWR was 3.56 ± 0.14 × 10−6 cm/s and paracellular transport across tight junctions was the main pathway across the Caco-2 monolayer. Therefore, the Pacific saury is a good material to prepare ACEIPs, but antihypertensive mechanism of peptide LEPWR on SHRs needs further investigation.

Identification and mechanistic study of four novel ACE inhibitory peptides from maize germ protein hydrolysates

Nowadays, much exertion has been given to identifying angiotensin-I converting enzyme inhibitory peptides (ACEIPs) from food by-products, while little attention has been paid to exploiting the potential use of maize germ proteins. Here, we identified four novel ACEIPs -PW, VTLL, LPGP, and SPGTAF, from maize germ protein hydrolysates. Inhibition assay demonstrated that these four peptides suppressed ACE activity with high potencies. Kinetics studies showed that PW inhibited ACE in a non-competitive manner with a Km of 1.15 mmol/L, whereas VTLL, LPGP, and SPGTAF were ACE substrate-competitive inhibitors with a constant Vmax of 0.005 △345 nm/min. Furthermore, molecular docking proved that PW mainly interacted with the key residues in the hydrophobic pocket of ACE through hydrogen bonding. Meanwhile, VTLL, LPGP, and SPGTAF docked at the catalytic domain of ACE and stabilized by hydrogen bonding with residues that coordinated Zn (II) or substrates. Our study suggests that the by-add product of maize could function as an alternative source for generating ACEIPs.

Structure identification and inhibitory mechanism evaluation of three novel angiotensin converting enzyme (ACE) inhibitory peptides from small-aroma chicken

Small-aroma chicken with a high protein content, is widely distributed in the mountainous area of Yunnan-Guizhou Plateau, China. In this work, three novel ACE-inhibitory peptides, Leu-Thr-Glu-Lys-Val-Val-Phe (LTQKVVF), Leu-Asp-Asp-His-Phe-Leu (LDDHFL), and Val-Pro-Gly-Pro-Glu-Pro-Lys-Pro (VPGPEPKP), were prepared from the Small-Aroma Chicken breast. The purification and identification protocol employed comprised ion-exchange chromatography, gel filtration chromatography, reverse phase-high performance liquid chromatography (RP-HPLC), and nano liquid chromatography-electrospray ionization–tandem mass (Nano-LC-ESI–MS/MS). Compared with VPGPEPKP and VPGPEPKP, LTQKVVF displayed noticeable ACE inhibitory activity, with IC50 values of 189.34 μM. What’s more, the Lineweaver-Burk plots revealed peptides LTQKVVF and LDDHFL acted as the mixed-competitive inhibitor while VPGPEPKP inhibited ACE in a manner similar to uncompetitive inhibition. The binding free energies of LTQKVVF, LDDHFL, and VPGPEPKP for ACE were −8.1 kcal/mol, −8.6 kcal/mol, and −9.6 kcal/mol, respectively. The strong inhibition of ACE by VPGPEPKP may be attributed to the interaction of hydrogen bonds, alkyl, and pi-alkyl, which formed by crucial residues of ACE.

Anchovy’s protein as a potential precursor of Angiotensin-I Converting Enzyme (ACE) inhibitory peptide and Dipeptidyl Peptidase-IV (DPP-IV) inhibitory peptide by an in silico approach

Protein from fish is known as the precursor of biologically active peptides that exert various health benefits such as antihypertensive, antitumor, and immunomodulatory properties. Hence, this study aimed to perform an extraction of anchovy, LC-MS/MS analysis and in silico evaluation of the major proteins in anchovies as potential precursors of biologically active peptides in addition to determining whether such peptides can be released by selected proteolytic enzymes. Anchovy was subjected to protein extraction followed by total soluble protein concentration determination using Bradford assay. The sample was subjected to in-solution trypsin digestion, which was then analysed by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). A bioinformatic approach by PEAKS Studio was used to identify the protein. A total of four anchovy’s proteins which are myosin light chain 1, V(D)J recombination-activating protein, 60 kDa chaperonin and heat shock protein 90AA1 were identified. Then, the identified proteins were subjected to in silico approach using the BIOPEP database. The biological potential of the theoretically released angiotensin-I converting enzyme (ACE) inhibitory peptides and dipeptidyl peptidase (DPP)-IV inhibitory peptides were predicted by determining the frequency of occurrence of fragments with a given activity. 60 kDa chaperonin and heat shock protein 90AA1 predicted the highest number of biological activities for ACE inhibitory peptides (284 and 264 fragments) and DPP-IV inhibitory peptides (395 and 409 fragments). The most promising enzyme for the generation of bioactive peptides from anchovy protein was anticipated to be pepsin (pH &gt; 2), which theoretically released a high number of DPP-IV inhibitory peptides and ACE inhibitory peptides through the action of in silico proteolysis. Overall, this work highlighted that anchovy protein could be a promising precursor of bioactive peptides that have ACE and DPP-IV inhibitory activities for developing functional food or nutraceutical products.

Purification and molecular docking of angiotensin converting enzyme-inhibitory peptides derived from corn gluten meal hydrolysate and from in silico gastrointestinal digestion

Corn gluten meal (CGM) was hydrolyzed by Alcalase with the degree of hydrolysis (DH) and protein recovery of 28.7 % and 67.7 %, respectively. Ultrafiltration revealed that the 3–10 kDa fraction (IC50 =15.98 µg/mL) involved potent ACE inhibitory peptides. The peptides in the fraction were further separated by size exclusion chromatography and reverse-phase chromatography. The novel peptide DLLGCS was identified to be the most active ACE inhibitor (IC50 =39.0 μM). The in silico digested peptide CS was approximately 4.5 times higher than its parent counterpart (IC50 =8.5 µM). Peptides CS and DLLGCS showed an uncompetitive inhibitor characteristic with Ki values of 12.52 and 11.40 µM, respectively. Based on molecular docking, both peptides interacted with the nonactive site of ACE, primarily via hydrogen bonds at Arg522, Asp121, Glu123 and Lys118 residues for DLLCGS and Glu162, Ser147 and Glu349 residues for CS. Therefore, peptides originated from CGM hydrolysates could exhibit a higher degree of inhibition against ACE enzyme upon gastrointestinal digestion, which is likely to be a potential source of bioactive peptides with ACE inhibitory activity.

Preparation and activity evaluation of angiotensin-I converting enzyme inhibitory peptides from protein hydrolysate of mulberry leaf.

Angiotensin-I converting enzyme (ACE) inhibitory peptides drew wide attention in the food industry because of their natural reliability, non-toxicity, and safety. However, the characteristics of ACE inhibitory peptides obtained from protein hydrolysate of mulberry leaf prepared by Flavourzyme were still unclear. Based on the single-factor test, the Plackett-Burman test and response surface test were used to determine the key factors affecting the ACE inhibition rate in mulberry leaf protein hydrolysate and the optimum conditions of enzymatic hydrolysis. The results showed that the optimum technical parameters were as follows: the ratio of material to liquid is 1: 25 (w / v, g/mL), the Flavourzyme to substrate ratio was 3,000 U/g, the temperature of enzymatic hydrolysis was 50°C, pH was 6.3, and the time of enzymatic hydrolysis was 2.9 h. The ACE inhibitory peptides in the mulberry leaf protein hydrolysates were purified by ultrafiltration and gel filtration, aiming to obtain the highest active component. The 12 peptide sequences were identified by reverse liquid chromatography-mass spectrometry, and then, they were docked to the crystal structure of human angiotensin-I converting enzyme (1O8A), and the interaction mechanisms of 12 peptide sequences and 1O8A were analyzed. The docking results showed that among the 12 peptide sequences, ERFNVE (792.37 Da), TELVLK (351.72 Da), MELVLK (366.72 Da), and FDDKLD (376.67 Da), all had the lowest docking energy, and inhibition constant. The chemosynthetic ERFNVE (IC50: 2.65 mg/mL), TELVLK (IC50: 0.98 mg/mL), MELVLK (IC50:1.90 mg/mL) and FDDKLD (IC50:0.70 mg/mL) demonstrated high ACE-inhibitory activity with competitive inhibition mode. These results indicated that the ACE-inhibiting peptides from mulberry leaf protein hydrolyzed (FHMP) had the potential activities to inhibit ACE and could be used as functional food or drugs to inhibit ACE. This work provides positive support for mining the biological activity of mulberry leaves in the treatment of hypertension.

Molecular docking and antihypertensive effects of a novel angiotensin-I converting enzyme inhibitory peptide from yak bone.

A novel angiotensin-converting enzyme (ACE) inhibitory peptide ser-ala-ser-val-ile-pro-val-ser-ala-val-arg-ala (SASVIPVSAVRA) was purified and identified from yak bone by Electrospray Ionization-Time of Flight-Mass Spectrometry (ESI-TOF-MS). Results in vitro showed that the peptide exhibited strong ACE inhibition activities with an IC50 of 54.22 μM. Molecular docking results showed the binding between the peptide SASVIPVSAVRA and ACE mainly driven by van der Waals forces, hydrogen bonds and metal receptor. Interestingly, the ACE inhibition activities of the peptide increased about 19% after digestion, but none of its metabolites showed stronger activity than it. The in vivo experiment showed that the antihypertensive effect of peptide SASVIPVSAVRA at dose of 30 mg/kg is nearly equal to Captopril at dose of 10 mg/kg to spontaneously hypertensive rats (SHRs). The antihypertensive effect mechanism of SASVIPVSAVRA should be further studied through plasma metabolomics and bioanalysis. Structure analysis of amino acids and peptides produced during digestion may help better understand the antihypertensive effect of peptides.

Purification and identification of antioxidant and angiotensin converting enzyme-inhibitory peptides from Guangdong glutinous rice wine

Guangdong glutinous rice wine, a type of Chinese yellow rice wine, is rich in a variety of bioactive peptides. In this study, polypeptides with antioxidant and angiotensin converting enzyme (ACE)-inhibitory activities were isolated from Guangdong glutinous rice wine, and their activities and molecular mechanisms were studied. The peptide fraction (F2-2), which exhibited the strongest antioxidant and ACE inhibitory activities, was separated by ultrafiltration and RP-HPLC. A total of 76 peptides were identified by LC-MS/MS, and four peptides with potential antioxidant activities were obtained: VLSGA (445.2536 Da), VISGA (445.2536 Da), MGKAA (476.2417 Da) and GHVAA (453.2336 Da). These four peptides showed significant antioxidant activity with EC50 values of 0.118 mg/mL, 0.056 mg/mL, 0.054 mg/mL and 0.027 mg/mL respectively, and effectively protected cells against oxidative damage. Molecular docking showed that all these four peptides could interact with key active sites on the receptor proteins CD38 and Keap1. Furthermore, these peptides showed good safety and stability according to in silico prediction.

First Report of Screening of Novel Angiotensin-I Converting Enzyme Inhibitory Peptides Derived from the Red Alga Acrochaetium sp.

ACE inhibitors generated from food proteins have recently become the most well-known subclass of bioactive peptides, and their bio-functionality can be a potential alternative to natural bioactive food components and synthetic drugs. The bioactivities of Acrochaetium sp., the red alga used in this investigation, have never been reported before. Screening of bioactive peptides from Acrochaetium sp. as ACE inhibitors were hydrolyzed with various proteolytic enzymes. Protein hydrolysates were fractionated separately using reversed phased (RP) and strong cation exchange (SCX) chromatography and identified as VGGSDLQAL (VL-9) using α-chymotrypsin. It comes from Phycoerythrin (PE), an abundant protein in a primarily red alga. The peptide VL-9 shows the ACE inhibitory activity with IC50 value 433.1 ± 1.08µM. The inhibition pattern showed VL-9 as a non-competitive inhibitor. Molecular docking simulation proved that VL-9 was non-competitive inhibition due to the interaction peptide and ACE was not in the catalytic site. Moreover, VL-9 derived from Acrochaetium sp. is a natural bioactive peptide that is safer and available for food protein; also, the ACE inhibitory peptide derived from Acrochaetium sp. could be the one alternative resource to develop functional food for combating hypertension.

Purification identification and function analysis of ACE inhibitory peptide from Ulva prolifera protein

In the present study, Ulva prolifera, an edible alga, was used to prepare angiotensin-I converting enzyme (ACE) inhibitory peptide. The algae protein was isolated and later hydrolyzed by five commercial enzymes (alcalase, papain, pepsin, trypsin, neutral protease), either individually or in combination. Hydrolysate, with the highest in vitro ACE inhibitory activity, was processed using the Sephadex-G100, ultrafiltration, HPLC-Q-TOF-MS, ADMET screening and molecular docking, respectively. The ACE inhibitory peptide DIGGL with a IC50 value of 10.32 ± 0.96 μM was then identified. The peptide against ACE by a non-competitive mode and mainly attributable to the three Conventional Hydrogen Bonds. It could activate Endothelial nitric oxide synthase activity in NO generation and reduce Endothelin-1 secretion induced by Angiotensin II in Human umbilical vein endothelial cells. Meanwhile, DIGGL could promote mice splenocytes proliferation, which was also effective when co-incubated with Con A or LPS, respectively. Besides, the anti-ACE peptide could remain active during the digestion of gastrointestinal proteases (pepsin-trypsin) in vitro.

Formation and inhibition mechanism of novel angiotensin I converting enzyme inhibitory peptides from Chouguiyu

Angiotensin I converting enzyme (ACE) inhibitory peptides from fermented foods exhibit great potential to alleviate hypertension. In this study, the peptide extract from Chouguiyu exhibited a good inhibition effect on ACE, and the inhibition rate was significantly enhanced after fermentation for 8 days. The ACE inhibitory peptides were further identified, followed by their inhibition and formation mechanisms using microbiome technology and molecular docking. A total of 356 ACE inhibitory peptides were predicted using in silico, and most ACE inhibitory peptides increased after fermentation. These peptides could be hydrolyzed from 94 kinds of precursor proteins, mainly including muscle-type creatine kinase, nebulin, and troponin I. P1 (VEIINARA), P2 (FAVMVKG), P4 (EITWSDDKK), P7 (DFDDIQK), P8 (IGDDPKF), P9 (INDDPKIL), and P10 (GVDNPGHPFI) were selected as the core ACE inhibitory peptides according to their abundance and docking energy. The salt bridge and conventional hydrogen bond connecting unsaturated oxygen atoms in the peptides contributed most to the ACE inhibition. The cleavage proteases from the microbial genera in Chouguiyu for preparing these 7 core ACE inhibitory peptides were further analyzed by hydrolysis prediction and Pearson's correlation. The correlation network showed that P7, P8, and P9 were mainly produced by the proteases from LAB including Lactococcus, Enterococcus, Vagococcus, Peptostreptococcus, and Streptococcus, while P1, P2, P4, and P10 were mainly Produced by Aeromonas, Bacillus, Escherichia, and Psychrobacter. This study is helpful in isolating the proteases and microbial strains to directionally produce the responding ACE inhibitory peptides.

Purification and Identification of a Novel Angiotensin Converting Enzyme Inhibitory Peptide from the Enzymatic Hydrolysate of Lepidotrigla microptera.

In this study, Lepidotrigla microptera were hydrolyzed with four different proteolytic enzymes (Papain, neutrase, flavourzyme, and alcalase), and their distribution of molecular weights and ACE-inhibitory activity were tested. The alcalase hydrolysates showed the maximum ACE-inhibitory activity. A novel ACE-inhibitory peptide was isolated and purified from Lepidotrigla microptera protein hydrolysate (LMPH) using ultrafiltration, gel filtration chromatography, and preparative high performance liquid chromatography (prep-HPLC). The amino acid sequence of the purified peptide was identified as Phe-Leu-Thr-Ala-Gly-Leu-Leu-Asp (DLTAGLLE), and the IC50 value was 0.13 mg/mL. The ACE-inhibitory activity of DLTAGLLE was stable across a range of temperatures (<100 °C) and pH values (3.0–11.0) and retained after gastrointestinal digestion. DLTAGLLE was further identified as a noncompetitive inhibitor by Lineweaver–Burk plot. The molecular docking simulation showed that DLTAGLLE showed a high binding affinity with ACE sites by seven short hydrogen bonds. As the first reported antihypertensive peptide extracted from alcalase hydrolysate of Lepidotrigla microptera, DLTAGLLE has the potential to develop functional food or novel ACE-inhibitor drugs.

Interaction mechanism of three egg protein derived ACE inhibitory tri-peptides and DPPC membrane using FS, FTIR, and DSC studies.

Understanding the interaction of food derived angiotensin converting enzyme (ACE) inhibitory peptides and intestinal epithelial cell membrane may help to improve their absorption. This research aimed to study the molecular interaction of ACE inhibitory tri-peptides ADF, FGR, and MIR with DPPC membrane during absorption process. The DPPC liposome was prepared and characterized, then used as a model membrane. The permeability of tri-peptides across the membrane was investigated using Fluorescence spectroscopy. The effect of tri-peptides on the structure and dynamics of DPPC bilayers was determined using Fourier transform infrared spectroscopy. The effect of tri-peptides on the phase transition temperature in the DPPC membrane was also analyzed using Differential scanning calorimetry. The results showed that ACE inhibitory tri-peptides ADF, FGR, and MIR can penetrate into both the membrane-water interface and hydrophobic region of DPPC bilayer, and the tri-peptide FGR have higher permeability across the membrane.