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Inhibition mechanism and model of an angiotensin I-converting enzyme (ACE)-inhibitory hexapeptide from yeast (Saccharomyces cerevisiae).

Ni H, Li L, Liu G, Hu SQ - PLoS ONE (2012)

Bottom Line: The hexapeptide was found to inhibit ACE in a non-competitive manner, as supported by the structural model.The displacement of the zinc ion from the active site resulted in the inhibition of ACE activity.This study provides a new inhibitory mechanism of ACE by a peptide which broads our knowledge for drug designing against enzyme targets.

View Article: PubMed Central - PubMed

Affiliation: Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, College of Light Industry and Food Sciences, South China University of Technology, Guangzhou, Guangdong, China.

ABSTRACT
Angiotensin I-converting enzyme (ACE) has an important function in blood pressure regulation. ACE-inhibitory peptides can lower blood pressure by inhibiting ACE activity. Based on the sequence of an ACE-inhibitory hexapeptide (TPTQQS) purified from yeast, enzyme kinetics experiments, isothermal titration calorimetry (ITC), and a docking simulation were performed. The hexapeptide was found to inhibit ACE in a non-competitive manner, as supported by the structural model. The hexapeptide bound to ACE via interactions of the N-terminal Thr1, Thr3, and Gln4 residues with the residues on the lid structure of ACE, and the C-terminal Ser6 attracted the zinc ion, which is vital for ACE catalysis. The displacement of the zinc ion from the active site resulted in the inhibition of ACE activity. The structural model based on the docking simulation was supported by experiments in which the peptide was modified. This study provides a new inhibitory mechanism of ACE by a peptide which broads our knowledge for drug designing against enzyme targets.

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The mode of tACE inhibition by QS.A. Lineweaver–Burk plot of the ACE activity in the presence of the hexapeptide; control (•), 100 µg/mL of QS (▴), and 200 µg/mL of QS (▪). B. The docking simulation of QS (green) binding to ACE (shown as sticks), and the overlap with captopril (cyan) in the crystal structure of the captopril-ACE complex The zinc ion (gray) is shown as nb_spheres. The figures were prepared using PYMOL software.
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pone-0037077-g006: The mode of tACE inhibition by QS.A. Lineweaver–Burk plot of the ACE activity in the presence of the hexapeptide; control (•), 100 µg/mL of QS (▴), and 200 µg/mL of QS (▪). B. The docking simulation of QS (green) binding to ACE (shown as sticks), and the overlap with captopril (cyan) in the crystal structure of the captopril-ACE complex The zinc ion (gray) is shown as nb_spheres. The figures were prepared using PYMOL software.

Mentions: The docking simulation of TPTQQS binding with ACE showed that Thr1, Thr3 and Gln4 are the key amino acids for the non-competitive inhibition: all of these amino acids interacted with residues in helix α1 of ACE. The three N-terminal helices (helices α1 to α3) form a lid-like structure (referred to as the lid) that has significant flexibility according to the B-factor [30]. Thr1, Thr3 and Gln4 can orient the peptide onto the lid structure, keeping the peptide out of the active site of tACE. The inhibition model was further verified by deleting Thr1, Pro2, Thr3 and Gln4 (Fig. 6). The kinetics experiment and the docking results for QS demonstrated that when the H-bonds between the peptide and the residues outside of the active site in tACE were deleted, the mode of inhibition became competitive, as demonstrated by the kinetics experiment (Fig. 6A). In this scenario, QS occupies the active site (S1′ and S2′) of tACE, which is occupied by the competitive inhibitor, captopril, in the crystal structure (Fig. 6B).


Inhibition mechanism and model of an angiotensin I-converting enzyme (ACE)-inhibitory hexapeptide from yeast (Saccharomyces cerevisiae).

Ni H, Li L, Liu G, Hu SQ - PLoS ONE (2012)

The mode of tACE inhibition by QS.A. Lineweaver–Burk plot of the ACE activity in the presence of the hexapeptide; control (•), 100 µg/mL of QS (▴), and 200 µg/mL of QS (▪). B. The docking simulation of QS (green) binding to ACE (shown as sticks), and the overlap with captopril (cyan) in the crystal structure of the captopril-ACE complex The zinc ion (gray) is shown as nb_spheres. The figures were prepared using PYMOL software.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3351391&req=5

pone-0037077-g006: The mode of tACE inhibition by QS.A. Lineweaver–Burk plot of the ACE activity in the presence of the hexapeptide; control (•), 100 µg/mL of QS (▴), and 200 µg/mL of QS (▪). B. The docking simulation of QS (green) binding to ACE (shown as sticks), and the overlap with captopril (cyan) in the crystal structure of the captopril-ACE complex The zinc ion (gray) is shown as nb_spheres. The figures were prepared using PYMOL software.
Mentions: The docking simulation of TPTQQS binding with ACE showed that Thr1, Thr3 and Gln4 are the key amino acids for the non-competitive inhibition: all of these amino acids interacted with residues in helix α1 of ACE. The three N-terminal helices (helices α1 to α3) form a lid-like structure (referred to as the lid) that has significant flexibility according to the B-factor [30]. Thr1, Thr3 and Gln4 can orient the peptide onto the lid structure, keeping the peptide out of the active site of tACE. The inhibition model was further verified by deleting Thr1, Pro2, Thr3 and Gln4 (Fig. 6). The kinetics experiment and the docking results for QS demonstrated that when the H-bonds between the peptide and the residues outside of the active site in tACE were deleted, the mode of inhibition became competitive, as demonstrated by the kinetics experiment (Fig. 6A). In this scenario, QS occupies the active site (S1′ and S2′) of tACE, which is occupied by the competitive inhibitor, captopril, in the crystal structure (Fig. 6B).

Bottom Line: The hexapeptide was found to inhibit ACE in a non-competitive manner, as supported by the structural model.The displacement of the zinc ion from the active site resulted in the inhibition of ACE activity.This study provides a new inhibitory mechanism of ACE by a peptide which broads our knowledge for drug designing against enzyme targets.

View Article: PubMed Central - PubMed

Affiliation: Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, College of Light Industry and Food Sciences, South China University of Technology, Guangzhou, Guangdong, China.

ABSTRACT
Angiotensin I-converting enzyme (ACE) has an important function in blood pressure regulation. ACE-inhibitory peptides can lower blood pressure by inhibiting ACE activity. Based on the sequence of an ACE-inhibitory hexapeptide (TPTQQS) purified from yeast, enzyme kinetics experiments, isothermal titration calorimetry (ITC), and a docking simulation were performed. The hexapeptide was found to inhibit ACE in a non-competitive manner, as supported by the structural model. The hexapeptide bound to ACE via interactions of the N-terminal Thr1, Thr3, and Gln4 residues with the residues on the lid structure of ACE, and the C-terminal Ser6 attracted the zinc ion, which is vital for ACE catalysis. The displacement of the zinc ion from the active site resulted in the inhibition of ACE activity. The structural model based on the docking simulation was supported by experiments in which the peptide was modified. This study provides a new inhibitory mechanism of ACE by a peptide which broads our knowledge for drug designing against enzyme targets.

Show MeSH