8/3/2019 paper eca

http://slidepdf.com/reader/full/paper-eca 1/7

 The molecular mechanisms of interactions between bioactive peptides and

angiotensin-converting enzyme

Daodong Pan a,b,⇑, Huiqing Guo b, Bo Zhao c,⇑, Jinxuan Cao a

a Faculty of Life Science & Biotechnology, Ningbo University, Ningbo 315211, Chinab Faculty of Food Science, Nanjing Normal University, Nanjing 210097, Chinac Faculty of Chemistry and Material Science, Nanjing Normal University, Nanjing 210097, China

a r t i c l e i n f o

 Article history:

Received 24 February 2011Revised 7 May 2011Accepted 10 May 2011Available online 15 May 2011

Keywords:

Milk protein peptidesACE-inhibitionMolecular mechanismsElucidate

a b s t r a c t

The ability of milk protein derived Ile-Pro-Ala (IPA), Phe-Pro (FP) and Gly-Lys-Pro (GKP) peptides to inhi-bit angiotensin I-converting enzyme (ACE), a protein with an important role in blood-pressure regulation,were verified in vitro and in vivo. This work elucidates the modes and molecular mechanisms of the inter-action of IPA, FP and GKP with ACE, including mechanisms that bind the peptides to the cofactor Zn2+. Itwas observed that the best docking poses obtained for IPA, FP and GKP were at the ACE catalytic site withvery similar modes of interaction, including the interaction with Zn2+. The interactions, includingH-bonds, hydrophobic, hydrophilic, and electrostatic interactions, as well as the interaction with Zn2+,were responsible for the binding between the bioactive peptides and ACE.

Ó 2011 Elsevier Ltd. All rights reserved.

In recent years, the search for natural components in food with

potential prophylactic and therapeutic effects has received greatinterest from researchers.1 Bioactive peptides are included in thiscategory because they exhibit antihypertensive, antioxidative,antithrombotic, opioidic, mineral carrier, antimicrobial, and immu-nomodulatory properties.2–4 Milk protein is known to be a richsource of bioactive peptides compared to other protein sourcessuch as animal (including fish) meat, wheat and soybean proteins.Among the bioactive peptides, angiotensin I-converting enzyme(ACE) inhibitory peptides and antihypertensive peptides have beenextensively researched, because hypertension is a major risk factorin cardiovascular disease, including heart disease.5,6 Ile-Pro-Ala(IPA), Phe-Pro (FP) and Gly-Lys-Pro (GKP) are antihypertensivepeptides crucial to cardiovascular homeostasis due to their inhibi-tion of ACE, a protein that plays a fundamental role in the renin–angiotensin system.4,7–9

ACE (EC 3.4.15.1) is a zinc metallopeptidase distributed in vas-cular endothelial, absorptive epithelial, neuroepithelial, and malegerminal cells.10–12 ACE acts on a wide range of substrates, display-ing both exopeptidase and endopeptidase activity.13 It cleaves thecarboxyl terminal His-Leu dipeptide from the inactive decapeptideangiotensin I to the active angiotensin II, a potent vasoconstrictor,which encourages hypertension. ACE also influences in an indirectmanner the kallikrein–kinin system by promoting the degradationand inactivation of bradykinin, which is a nonapeptide involved in

blood-pressure control and inflammation. There are two isoforms

of ACE transcribed by the same gene; a larger one with 1277 aminoacids, which is expressed in most tissues and is referred to as so-matic ACE (sACE), and a smaller one which is composed of 701amino acids and is found in adult testis. The smaller ACE is referredto as testis ACE (tACE).14,15 Somatic ACE is composed of twohomologous catalytic domains (N and C), each with a functional ac-tive site and with distinct physiochemical and functional proper-ties.16 These two ACE domains differ in both substrate andinhibitor specificity and chloride activation.17,18 Although both do-mains are efficient in angiotensin I cleavage, inhibition of the N do-main with RXP407 (an ACE-N-selective inhibitor) has no effect onblood pressure. This suggests that the C- domain is the dominantangiotensin-converting site.14,19 Testis ACE exhibits only one do-main, which is essentially identical to the C domain of sACE.15,20

Considering that ACEs are an evolutionary family of proteins,20 astructural comparison of tACE and Drosophila homolog of ACE(AnACE) has revealed a close homology between them, exhibiting42% amino acid sequence identity.13,20 AnACE exhibits propertiesvery similar to those of the human C domain ACE11 and AnACEactivity is also inhibited by highly potent human ACE inhibitors.20

Most current ACE inhibitors, such as captopril, lisinopril andenalaprilat, are potent inhibitors of both the C and N domains of sACE and tACE.15,18 These molecules interact with the enzymethrough hydrogen bonds and hydrophobic interactions at theACE subsites S1, S2, S10 and S20, but also directly interact withthe catalytic Zn2+ ion.14,18,19,21

Nutraceuticals was used to be an auxiliary drug in hypertensiontreatment, but there are few antihypertensive products based on

0960-894X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.doi:10.1016/j.bmcl.2011.05.033

⇑ Corresponding authors. Tel.: +86 0 574 87600737; fax: +86 0 574 87608347.

E-mail address: daodongpan@163.com (D. Pan).

Bioorganic & Medicinal Chemistry Letters 21 (2011) 3898–3904

Contents lists available at ScienceDirect

Bioorganic & Medicinal Chemistry Letters

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / b m c l

8/3/2019 paper eca

http://slidepdf.com/reader/full/paper-eca 2/7

milk-derived peptides currently available.22 Milk-derived peptidescan be liberated during food processing by chemical, physical orenzymatic methods.3 The latter can be achieved through the actionof proteolytic enzymes during the fermentation of milk or uponenzymatic hydrolyzes of milk proteins in vitro.23 Hydrolysates of whole-milk protein, caseinates, whey proteins, and fractions en-richedin individualmilk proteinsare a good source of bioactivemilkpeptides, and in particular, ACE-inhibitory peptides.9 Some authorshave proposed thattri-peptidesexhibithigher ACE-inhibitoryactiv-ity.24 Peptide sequences containing hydrophobic amino acid resi-dues or proline residues at the C terminus are potent ACEinhibitors resistant to degradation by digestive enzymes.4,12,22,24

In fact, it has been shown that binding to ACE is strongly influencedby the C terminus of tripeptide sequence.24,25

Casein-derived FP (b-casein: f62–63, f157–158, f205–206) andwhen protein derived IPA (b-lactoglobulin: f78–80) and GKP(b-microglobulin: f18–20) can be produced in vitro or in vivothrough enzymatic hydrolysis of milk proteins (e.g., casein) bydigestive enzymes (e.g., pepsin or trypsin) or by microbial fermen-tation of milk using a proteolytic system of lactic-acid bacteria(e.g., Lactococcus lactis, Lactobacillus helveticus).4 In vitro studiesdemonstrated that IPA, FP and GKP inhibit ACE activity. The con-centrations of IPA, FP and GKP needed to inhibit 50% of the ACE(IC50) activity were 141, 315 and 352 lM, respectively.9 In vivostudies with milk products containing these peptides were per-formed using spontaneously hypertensive rats (SHR).11 Attenua-tion of hypertension was observed after six weeks by gastric-intubation treatment of IPA, FP and GKP.8 The systolic blood pres-sure (SBP) of SHR decreased by 31, 27 and 26 mmHg, respectively,at dosages of 8.0 mg/kg.11 These results suggest that they may bethe auxiliary drugs once they are further developed andcommercialized.

Despite the interest in bioactive peptides as an alternative forthe control of mild hypertension, the exact mode of interactionand the molecular mechanisms between these peptides and ACEare not understood and their promise is mainly supported by data

from in vitro and in vivo ACE-inhibition studies. In this work, weattempt to elucidate how IPA, FP and GKP exert their antihyperten-sive effects. This was accomplished by automated molecular dock-ing of the bioactive peptides at the ACE catalytic site in thepresence of cofactors (chloride and zinc ions), and by analyzingthe position, type and energy of the interactions.

The three-dimensional structure of native-human ACE was im-ported from the Protein Data Bank (PDB: 1O8A). The structures of ligands (bioactive peptides) were generated with Accelrys Discov-ery Studio 2.1 software and energy minimized with the CHARMmprogram using steepest descent and conjugate gradient tech-niques. Before the docking procedure, water molecules were re-moved from the protein-crystal structure.

Automated molecular docking studies of the bioactive peptides

(IPA, FP and GKP) at the ACE-binding site were performed with theFlexible Docking tool of DS2.1 software, in the presence of cofac-tors (zinc and chloride ions).The active site was obtained withthe Binding Site tool. The docking runs were performed with a ra-dius of 8 ÅA

0

, with the coordinates x: 38.977; y: 38.645 and z : 50.183.Evaluation of the molecular docking was performed according tothe scores of several scoring functions, including LibDockScore,CDocker Energy, CDocker Interaction Energy, LigScore1, LigScore2,PLP1, PLP2, Jain, PMF, and PMFO4. The implicit solvent model Dis-tance-Dependent Dielectrics was used in this work. The softwarereturned data for the 20 best poses obtained in terms of the bind-ing energy values. The software Accelrys Discovery Studio 2.1 wasused to identify the hydrogen bonds, and the hydrophobic, hydro-philic and electrostatic interactions between residues at the ACE

active site and the peptide poses.

The study of the coordination between peptides and Zn(II) wasalso possible. The distance between the peptides and Zn(II) was ob-tained from the docking results. The X-ray crystallographic struc-ture of the ACE protein is available. The chemical structuralformulas of bioactive peptides were generated using the softwareChemDraw Ultra 8.0 (Fig. 1). Based on ACE’s three-dimensionalstructure, the possible ACE active sites were obtained via a bindingsite procedure. According to ACE’s catalytic mechanism and rele-vant experimental reports, ACE’s active site was identified. The sitecontains 19 amino acid residues: His353, Ala354, Ser355, Ala356,His383, Glu384, His387, Phe391, Pro407, His410, Glu411, Phe512,His513, Ser516, Ser517, Val518, Pro519, Arg522, and Tyr523. Thezinc(II) ion is also an important component in ACE catalysis14

and is partly responsible for the binding strength between ACEand their inhibitors.26 A complete inactivation of the enzyme wasobserved in studies where mutations of metal-coordinating resi-dues in human sACE were created, providing evidence for the roleof zinc ions in ACE activity.20

The docking study of the tripeptide IPA at the ACE catalytic sitein the presence of the cofactor Zn(II) showed a best pose (pose 14)with a binding energy value of À611.63 kJ/mol. The best pose wasstabilized by hydrogen bonds, and hydrophobic, hydrophilic (Fig. 3a) and electrostatic interactions (Table 6) with ACE residues.The values for the hydrogen bond parameters of the best pose(IPA) are shown in Table 1.

The amine group of the N-terminal isoleucine residue estab-lished hydrogen bonds with the –OH from Ser355 and the carbonylgroup of Ala356. The carbonyl group of the proline residue alsointeracted with the residue Ala356 via hydrogen bonding. Theamine group of the alanine residue contacted with the residuesAla354 and Glu384 via hydrogen bonds. The carboxylic group of the C-terminal alanine residue established hydrogen bonds withthe –OH from Tyr 523. On the basis of the hydrogen bond param-eters, these H-bond interactions established with Ala354, Ala356(N), Ser355 and Tyr523 presented more potent interactions, whichgreatly contributed to stabilization (Table 4).

The molecular docking of IPA on the ACE binding site revealedthat IPA, via hydrophobic interactions makes contact with residuesincluding Ala354, Ala356, Phe391, Phe512, and Val518, and viahydrophilic interactions with residues including His353, 383,387, 410, 513, Glu384, 411, and Arg522. The aromatic portion of Tyr 523 also contributed to stabilization.

The research shows that, the interactions between the ACEinhibitors and the Zn2+ at the ACE active site usually play veryimportant roles and therefore make ACE deactivation.19 In ACE,the zinc ion tetra-coordinated with the three residues (His383,Glu411 and His387) and CH3COOXT ( Fig. 2). The values of bondlength are shown in Table 5. After docking, we measured the dis-tances between the zinc ion and its surrounding atoms. We foundthat the initial values of bond length made some changes and some

atoms of the peptides were nearly closed to the zinc ion. Theseatoms and their distances were obtained (Table 5). The distanceof O15 (IPA) and Zn2+is 2.057 ÅA

0

, which is nearly closed to the cova-lent radius summation (2.14 ÅA

0

) of the oxygen (1.4 ÅA0

) and the zincion (0.74 ÅA

0

).20 This result suggests that the IPA may have the abilityto coordinate with the zinc ion through the carbonyl group of theproline residue. Together with the three residues (His383, Glu411and His387) coordinated with zinc(II) the IPA around the zinc ionformed a distorted tetrahedral geometry (Fig. 3b).

The dipeptide FP docked at the ACE catalytic site in the presenceof the cofactor Zn(II). H-bonds, and hydrophobic, hydrophilic(Fig. 3c) and electrostatic interactions (Table 6) with this enzymewere suggested. The best docking pose obtained (pose 19) pre-sented a binding energy of  À713.89 kJ/mol. The values for the

hydrogen bond parameters of the best pose are shown in Table 2.

D. Pan et al. / Bioorg. Med. Chem. Lett. 21 (2011) 3898–3904 3899

8/3/2019 paper eca

http://slidepdf.com/reader/full/paper-eca 3/7

The N-terminal amine group of phenylalanine established twoH-bond interactions with a histidine residue (His353): one withan alanine residue (Ala354) and one with Ser355. An additionalH-bond interaction was observed between the carboxylic groupof the C-terminal proline residue and Arg522. Arg522 greatly con-

tributed to stabilization via the H-bond. As observed for IPA, FPalso established additional hydrophobic interactions with residuesincluding Ala354, Ala356, Phe391, Phe512, and Val518, and hydro-philic interactions with residues including His353, 383, 387, 410,513, Glu384, 411, and Arg522. Similarly, there were some changesafter FP entered the ACE active site. The CH3COOXT was replacedby the carboxylic group of the C-terminal proline of FP (Table 5).The coordination atom of Glu411 (ACE) was no longer OE1 butOE2, and this change in coordination atoms may help stabilizethe complex and therefore benefit the ACE-inhibition properties.Together with the three residues (His383, Glu411 and His387)coordinated with zinc ion in ACE the FP around the zinc ion formeda distorted tetrahedral geometry (Fig. 3d).

The molecular docking between ACE and GKP revealed that thebinding energy value of the best pose was

À1335.79 kJ/mol. The

best pose was stabilized by hydrogen bonds, and hydrophobic,

hydrophilic (Fig. 3e) and electrostatic interactions (Table 6) withACE residues. The values for the hydrogen bond parameters of the best pose (GKP) are shown in Table 3.

The N-terminal amine group of glycine established two H-bondinteractions with glutamine residue (Glu384) and Ala354. Theamine group of the first peptide bond between the glycine andlysine residuesestablished anH-bondinteractionwith histidine res-idue (His353). AnadditionalH-bondinteractionwas observedin the

N

C

O

H3N

CNH

O O

O

IPA

C

O

N

NH3

O

O

FP

C

O

N

O

O

NH

C

O

H3N

H3N

GKP

Fig. 1. The chemical structural formulas of bioactive peptides.

 Table 1

Hydrogen bonds observed between ACE and the best IPA pose obtained from docking

results

IPA X–HÁ Á Á

Y  d (X–H) d (HÁ Á Á

Y) d (XÁ Á Á

Y) d (XÁ Á Á

Y)

Ala354:OÁ Á ÁH42–N16 1.00 2.07 3.01 155.60Ser355:OGÁ Á ÁH23–N1 1.04 2.42 3.32 144.20Ala356:OÁ Á ÁH22–N1 1.04 2.07 2.58 107.10Ala356:OÁ Á ÁH23–N1 1.04 2.40 2.58 87.60Ala356:N–HNÁ Á ÁO8 0.99 2.08 3.02 157.10Glu384:OE2Á Á ÁH42–N16 1.00 2.25 2.85 116.70Tyr523:OH–HHÁ Á ÁO21 0.95 2.03 2.89 148.80

Fig. 2. Details of the zinc ion tetra-coordinated with the ACE residues beforedocking.

3900 D. Pan et al. / Bioorg. Med. Chem. Lett. 21 (2011) 3898–3904

8/3/2019 paper eca

http://slidepdf.com/reader/full/paper-eca 4/7

carbonyl group of the second peptide bond between the lysine andproline residues and the –OH from Tyr523. The carboxylic group of the C-terminal proline residue also established a hydrogen bondwith the amide group of Arg522. Based on the hydrogen bond

parameters, the H-bond interactions established with His353,

Ala354,Glu384(OE1), Arg522, andTyr523presentedpotentinterac-tions that greatly contributed to stabilization. These three poseswere very similar in terms of their hydrophobic and hydrophilicinteractions with ACE. In GKP it was the carbonyl group of the first

peptide bond that replaced the CH3COOXT (Table 5).The three

Fig. 3. Details of the interaction between ACE and (a) IPA, (c) FP and (e) GKP after automated docking of the peptides at the ACE-active site. ACE hydrophobic residues arerepresented in blue, hydrophilic residues in yellow, other residues present on binding site in gray, andzinc atomsin purple. Hydrogenbonds are shown in green dashedlinesand zinc coordinationbonds in gray bold lines.(a) Binding of IPApeptideto ACE, (c)bindingof FP peptide to ACE, (e)binding of GKP peptide to ACE. Schematic view of (b)IPA,(d) FP and (f) GKP zinc coordination at the ACE-active site (image obtained with Accelrys DS Visualizer software).

D. Pan et al. / Bioorg. Med. Chem. Lett. 21 (2011) 3898–3904 3901

8/3/2019 paper eca

http://slidepdf.com/reader/full/paper-eca 5/7

residues (His383, Glu411 and His387) and their atoms coordinatedwith the zinc ion made no changes after the GKP entering (Fig. 3f).

As shown in Table 6, electrostatic energy played a more impor-tant role in the interactions between the bioactive peptides andACE than did van der Waals energy. In the interaction of ACE withIPA, the six residues from the ACE active site, Ala354 (À23.14 kJ/mol), Ser355 (À32.55 kJ/mol), Ala356 (À74.31 kJ/mol), His383(À36.65 kJ/mol), His513 (À33.64 kJ/mol), and Tyr523 (À55.52 kJ/mol) greatly contributed to stabilization. Ala356 and Tyr523 wereespecially important components in the ACE active site and were

partly responsible for the binding strength. In FP, it is the residues,Ala354 (À71.55 kJ/mol), Glu384 (À65.61 kJ/mol), His410 (À38.03kJ/mol), Arg522 (À142.67 kJ/mol), and Tyr (À35.61 kJ/mol) thatstabilized the interaction between FP and ACE. Of the above resi-dents, Ala354, Glu384 and Arg522 made the greatest contributionto stabilization. For GKP, the eight residues from the ACE activesite, His353 (À31.46 kJ/mol), Ala354 (À78.87 kJ/mol), Ala356(À21.63 kJ/mol), His410 (À66.78 kJ/mol), His513 (À31.38 kJ/mol),Pro519 (À45.81 kJ/mol), Arg522 (À200.46 kJ/mol) and Tyr523(À58.32 kJ/mol) greatly contributed to stabilization. Ala354,His410, Arg522 and Tyr523 were especially important componentsin the ACE active site. In fact, these three poses are very similar interms of the residues from the ACE active site established via H-bonds and electrostatic interactions, specifically, Ala354, Ala356,Arg522, and Tyr523.

As exhibited in Figure 4(a–c), the best peptide docking site waslocated in the deep narrow channel of the ACE active site. Bindingenergy was believed to be the best choice as a parameter for iden-tifying the best binder to a given target between a set of differentligands.11,27 The peptide IPA presented the lowest IC50 value(IC50 = 141 lM) but the highest binding energy (À611.63 kJ/mol).The peptide GKP presented the highest IC50 value (IC50 = 352 lM)but the lowest binding energy (À1335.79 kJ/mol). The IC50 valueand binding energy of FP were 315lM and 713.89 kJ/mol, respec-tively. Both FP values were between those for IPA and GKP. Wefound no correlation between the lowest binding energies obtainedand the lowest known IC50 values.

The IPA, FP and GKP have the potential to inhibit ACE via verysimilar modes of inhibition. Their promise rests, in part, dependenton their small size and generally high hydrophobic, hydrophilicand electrostatic character. The three peptides poses reveal inter-actions of peptides with ACE via H-bonding and electrostatic inter-

 Table 2

Hydrogen bonds observed between ACE and the best FP pose obtained from docking

results

FP X–HÁ Á ÁY  d (X–H) d (HÁ Á ÁY) d (XÁ Á ÁY) (XHY)

His353:NE2Á Á ÁH20–N1 1.04 2.21 2.70 106.80His353:NE2Á Á ÁH21–N1 1.04 2.49 2.70 89.80Ala354:OÁ Á ÁH20–N1 1.04 2.03 2.77 125.90Ser355:OGÁ Á ÁH22–N1 1.04 2.29 3.05 129.50

Arg522:NH2–HH22Á Á ÁO19 1.00 2.22 2.99 132.60

 Table 3

Hydrogen bonds observed between ACE and the best GKP pose obtained from docking

results

GKP X–HÁ Á ÁY  d (X–H) d (HÁ Á ÁY) d (XÁ Á ÁY) (XHY)

His353:NE2Á Á ÁH27–N5 1.00 2.46 3.46 177.40Ala354:OÁ Á ÁH24–N1 1.04 1.82 2.76 148.90Glu384:OE1Á Á ÁH22–N1 1.04 2.13 3.14 162.60Glu384:OE2Á Á ÁH22–N1 1.04 1.92 2.69 128.00Arg522:NH2–HH22Á Á ÁO21 1.00 2.11 3.02 150.70Tyr523:OH–HHÁ Á ÁO13 0.95 2.19 3.07 154.40

 Table 4

Hydrogen bonds observed between the best bioactive peptide poses obtained from docking results with ACE

Hydrogen bonds caused by molecular docking

IPA(14) pose Amount FP(19) pose Amount GKP(03) pose Amount

His353 NE2 Â —p 

2p 

1⁄Ala354 O

p 1⁄

p 1

p 1⁄

Ala356 Op 

2 Â — Â —Ala356 N

p 1⁄ Â — Â —

Ser355 OGp 

1⁄p 

1 Â —Glu384 OE1 Â — Â —

p 1⁄

Glu384 OE2p 

1 Â —p 

1Tyr523 OH

p 1⁄ Â —

p 1⁄

Arg522 NH2 Â —p 

1⁄p 

1⁄p 

Existence of hydrogen bond interactions. Nonexistence of hydrogen bond interactions.* Strong hydrogen bond interactions.

 Table 5

Atoms from ACE residues and bioactive peptides (poses obtained from docking results) involved in interaction with Zn2+ before and after docking

Residues involved in interaction with Zn2+

Initial ACE Distance (ÅA0

) Pose 14 IPA Distance (ÅA0

) Pose 19 FP Distance (ÅA0

) Pose 03 GKP Distance (ÅA0

)

His 383 NE2p 

2.02p 

2.26p 

2.33p 

2.19His 387 NE2

p 2.06

p 2.15

p 2.17

p 2.11

Glu 411 OE1p 

1.97p 

2.12 Â —p 

2.14Glu 411 OE2 Â — Â —

p 2.11 Â —

CH3COOXTp 

2.06 Â — Â — Â —IPA O15 Â —

p 2.06 Â — Â —

FP O18 Â — Â —p 

2.28 Â —GKP O4 Â — Â — Â —

p 2.15

p 

ACE residues involved in interaction with Zn2+

. ACE residues not involved in interaction with Zn2+.

3902 D. Pan et al. / Bioorg. Med. Chem. Lett. 21 (2011) 3898–3904

8/3/2019 paper eca

http://slidepdf.com/reader/full/paper-eca 6/7

actions with four residues: Ala354, Ala356, Arg522, and Tyr523.Especially the charged amine groups of the N-terminal were thesteering groups in amino acid residues. The carbonyl groups of the IPA, FP and IPP were closed to the zinc ion and may be coordi-nating with zinc ion; it indicated that the atoms coordinating withzinc are equivalent and the tetrahedral coordination geometryresembles a captopril interaction. Binding energy does not directlycorrelate with the experimental IC50 values in some cases, sinceestimating binding energy is a challenging task. The performance

of site mutational changes in ACE able to suppress both drug andpeptide inhibition may also provide more information about theinteraction modes of antihypertensive products and ACE.

 Acknowledgment

This work was supported by the Natural Science Funding of China (project 30972130), the NSF projects of Jiangsu (BK2009403) and Ningbo (2009A610180) of China, Science and Tech-

 Table 6

Electrostatic energy, van der Waals energy and total potential energy (kJ/mol) between the best bioactive peptides poses obtained from docking results with ACE

Residue IPA FP GKP

E ele E vdw E total E ele E vdw E total E ele E vdw E total

Total 90.63 À134.77 À44.14 73.14 1738.28 1811.42 À464.72 1559.04 1094.33His353 6.19 À9.12 À2.93 55.77 84.81 140.58 À20.38 À11.09 À31.46Ala354 À12.51 À10.63 À23.14 À73.89 À11.00 À84.89 À71.55 À7.32 À78.87Ser355

À14.18

À18.37

À32.55 6.65

À10.88

À4.23 3.60

À15.65

À12.05

Ala356 À67.99 À6.32 À74.31 À4.18 À10.25 À14.43 À16.28 À5.36 À21.63His383 À26.36 À10.29 À36.65 15.06 1442.64 1457.71 13.14 À5.36 7.78Glu384 3.72 À11.72 À7.99 À57.03 À8.58 À65.61 À422.67 1102.27 679.61His387 19.41 À13.14 6.28 24.98 47.57 72.55 42.17 À9.29 32.89Phe391 30.71 À3.64 27.07 10.29 À3.05 7.24 19.08 À1.13 17.95Pro407 15.65 À0.67 14.98 7.07 À0.71 6.36 5.73 À1.00 4.73His410 0.33 À7.28 À6.95 À32.97 À5.06 À38.03 À57.03 À9.75 À66.78Glu411 136.19 À9.08 127.11 269.28 243.09 512.37 324.13 520.82 844.96Phe512 À12.47 À4.48 À16.95 2.85 À2.47 0.38 20.13 21.80 41.92His513 À27.36 À6.28 À33.64 À4.10 À4.44 À8.54 À25.10 À6.28 À31.38Ser516 8.20 À0.42 7.78 12.76 À0.17 12.59 14.85 À3.39 11.46Ser517 À9.16 À0.17 À9.33 À6.36 À0.08 À6.44 8.45 À0.46 7.99Val518 24.43 À5.06 19.37 1.30 À3.93 À2.64 À2.22 À5.98 À8.20Pro519 9.29 À0.67 8.62 5.23 À0.50 4.73 À44.64 À1.17 À45.81Arg522 49.45 À4.85 44.60 À135.31 À7.36 À142.67 À209.95 9.50 À200.46Tyr523 À42.93 À12.59 À55.52 À24.27 À11.34 À35.61 À46.19 À12.13 À58.32

Fig. 4. General overview of best docking poses (gray) at the ACE catalytic site: (a) IPA, (b) FP and (c) GKP poses (images obtained with Accelrys DS Visualizer software).

D. Pan et al. / Bioorg. Med. Chem. Lett. 21 (2011) 3898–3904 3903

8/3/2019 paper eca

http://slidepdf.com/reader/full/paper-eca 7/7

nology Department projects of Zhejiang (2010C12015) of China,and the K.C. Wong Magna Fund at Ningbo University.

References and notes

1. Korhonen, H.; Pihlanto, A. Curr. Pharm. Des. 2003, 9, 1297.2. Clare, D. A.; Swaisgood, H. E. J. Dairy Sci. 2000, 83, 1187.3. Smacchi, E.; Gobbetti, M. Food Microbiol. 2000, 17 , 129.4. Korhonen, H.; Pihlanto, A. Int. Dairy J. 2006, 16 , 945.5. FitzGerald, R. J.; Meisel, H. Br. J. Nutr. 2000, 84, S33.6. Kitts, D. D.; Weiler, K. Curr. Pharm. Des. 2003, 9, 1309.7. Tulipano, G.; Sibilia, V.; Caroli, A. M.; Cocchi, D. Peptides 2011, 32, 835.8. Saito, T. Exp. Med. Biol. 2008, 606 , 295.9. FitzGerald, R. J.; Murray, A. M.; Walsh, D. J. J. Nutr. 2004, 134, 980S.

10. Wei, L.; Clauser, E.; Alhenc-Gelas, F.; Corvol, P. J. Biol. Chem. 1992, 267 , 13398.11. Acharya, K. R.; Sturrock, E. D.; Riordan, J. F.; Ehlers, M. R. W. Nat. Rev. Drug Disc.

2003, 2, 891.12. Li, G. H.; Le, G. W.; Shi, Y. H.; Shrestha, S. Nutr. Res. 2004, 24, 469.13. Sturrock, E. D.; Natesh, R.; Van Rooyen, J. M. Cell. Mol. Life Sci. 2004, 61, 2677.14. Natesh, R.; Schwager, S. L. U.; Sturrock, E. D.; Acharya, K. R. Nature 2003, 421,

551.

15. Tzakos, A. G.; Galanis, A. S.; Spyroulias, G. A.; Cordopatis, P.; Manessi-Zoupa, E.;Gerothanassis, I. P. Protein Eng. 2003, 16 , 993.

16. Corradi, H. R.; Schwager, S. L. U.; Nchinda, A. T.; Sturrock, D.; Acharya, K. R. J.Mol. Biol. 2006, 357 , 964.

17. Georgiadis, D.; Beau, F.; Czarny, J.; Cotton, J.; Yiotakis, A.; Dive, V. Circ. Res.2003, 93, 148.

18. Natesh, R.; Schwager, S. L. U.; Evans, H. R.; Sturrock, E. D.; Acharya, K. R.Biochemistry 2004, 43, 8718.

19. Zhao, Y. H.; Li, B. F.; Liu, Z. Y. Process Biochem. 2007, 42, 1586.20. Oxtoby, D. W.; Gillis, H. P. Nachr. Princ. Mod. Chem. 1986.

21. Andújar-Sánchez, M.; Cámara-Artigas, A.; Jara-Pérez, V. Biophys. Chem. 2004,111, 183.

22. Lopez-Fandiño, R.; Otte, J.; Van Camp, J. Int. Dairy J. 2006, 16 , 1277.23. Otte, J.; Shalaby, S. M.; Zakora, M.; Pripp, A. H.; El-Shabrawy, S. A. Int. Dairy J.

2007, 17 , 488.24. Wu, J.; Aliko, R. E.; Nakai, S. J. Agric. Food. Chem. 2006, 54, 732.25. Jäkälä, P.; Vapaatalo, H. Pharmaceuticals 2010, 3, 251.26. Corradi, H. R.; Chitapi, I.; Sewell, B. T.; Georgiadis, D.; Dive, V.; Sturrock, E. D.;

Acharya, K. R. Biochemistry 2007, 46 , 5473.27. Thomsen, R.; Christensen, M. H. J. Med. Chem. 2006, 49, 3315.

3904 D. Pan et al. / Bioorg. Med. Chem. Lett. 21 (2011) 3898–3904