9QAM | pdb_00009qam

Human angiotensin-1 converting enzyme C-domain in complex with ciprofloxacin


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 
    0.227 (Depositor), 0.239 (DCC) 
  • R-Value Work: 
    0.199 (Depositor), 0.210 (DCC) 

Starting Model: experimental
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Ligand Structure Quality Assessment 


This is version 1.0 of the entry. See complete history


Literature

Ciprofloxacin Inhibits Angiotensin I‐Converting Enzyme (ACE) Activity by Binding at the Exosite, Distal to the Catalytic Pocket.

Gregory, K.S.Ramasamy, V.Sturrock, E.D.Acharya, K.R.

(2025) ACS Bio Med Chem Au 5: 852-859

  • DOI: https://doi.org/10.1021/acsbiomedchemau.5c00089
  • Primary Citation of Related Structures:  
    9QAM

  • PubMed Abstract: 

    Human somatic angiotensin I-converting enzyme is a key zinc metallopeptidase in cardiovascular regulation that hydrolyzes angiotensin peptides (Ang I, Ang II), as well as other vasoactive peptides, including kinins (e.g., bradykinin), substance P, the acetylated tetrapeptide Ac-Ser-Asp-Lys-Pro, and the amyloid ß-peptide. Because of its enzymatic promiscuity, ACE and its substrates and products affect many physiological processes, including blood pressure control, hemopoiesis, reproduction, renal development/function, fibrosis, and immune response. ACE inhibitors are among the most important therapeutic agents available today for the treatment of hypertension, heart failure, coronary artery disease, renal insufficiency, and general atherosclerosis. However, they need much improvement because of the side effects seen in patients with long-term treatment due to nonselective inhibition of the N- and C-domains of ACE (referred to as nACE and cACE, respectively). Here, we report that ACE activity can be inhibited by ciprofloxacin, a potent fluoroquinolone antibiotic (IC 50 202.7/ K i 33.8 μM for cACE). In addition, the high-resolution crystal structure of cACE in complex with ciprofloxacin reveals that it binds at an exosite away from the active site pocket, overlapping the position of a potential allosteric site with a different binding mode. The detailed structural information reported here will provide a useful scaffold for the design of future potent allosteric inhibitors.


  • Organizational Affiliation
    • Department of Life Sciences, University of Bath, Claverton Down, Bath BA2 7AY, U.K.

Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Angiotensin-converting enzyme, soluble form578Homo sapiensMutation(s): 6 
Gene Names: ACEDCPDCP1
EC: 3.4.15.1
UniProt & NIH Common Fund Data Resources
Find proteins for P12821 (Homo sapiens)
Explore P12821 
Go to UniProtKB:  P12821
PHAROS:  P12821
GTEx:  ENSG00000159640 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP12821
Glycosylation
Glycosylation Sites: 1Go to GlyGen: P12821-1
Sequence Annotations
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  • Reference Sequence
Oligosaccharides

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Entity ID: 2
MoleculeChains Length2D Diagram Glycosylation3D Interactions
2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-[alpha-L-fucopyranose-(1-6)]2-acetamido-2-deoxy-beta-D-glucopyranoseB [auth C]3N-Glycosylation
Entity ID: 3
MoleculeChains Length2D Diagram Glycosylation3D Interactions
2-acetamido-2-deoxy-beta-D-glucopyranose-(1-3)-1-deoxy-alpha-D-mannopyranoseC [auth B]2N/A
Small Molecules
Ligands 8 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
CPF (Subject of Investigation/LOI)
Query on CPF

Download Ideal Coordinates CCD File 
J [auth A],
K [auth A]
1-CYCLOPROPYL-6-FLUORO-4-OXO-7-PIPERAZIN-1-YL-1,4-DIHYDROQUINOLINE-3-CARBOXYLIC ACID
C17 H18 F N3 O3
MYSWGUAQZAJSOK-UHFFFAOYSA-N
NXA
Query on NXA

Download Ideal Coordinates CCD File 
H [auth A]N-CARBOXYALANINE
C4 H7 N O4
JCVPWRQVQNVNGU-REOHCLBHSA-N
PEG
Query on PEG

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N [auth A]DI(HYDROXYETHYL)ETHER
C4 H10 O3
MTHSVFCYNBDYFN-UHFFFAOYSA-N
MLI
Query on MLI

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I [auth A]MALONATE ION
C3 H2 O4
OFOBLEOULBTSOW-UHFFFAOYSA-L
IMD
Query on IMD

Download Ideal Coordinates CCD File 
G [auth A]IMIDAZOLE
C3 H5 N2
RAXXELZNTBOGNW-UHFFFAOYSA-O
ZN (Subject of Investigation/LOI)
Query on ZN

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D [auth A]ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
EDO
Query on EDO

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L [auth A],
M [auth A]
1,2-ETHANEDIOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
CL
Query on CL

Download Ideal Coordinates CCD File 
E [auth A],
F [auth A]
CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
CSO
Query on CSO
A
L-PEPTIDE LINKINGC3 H7 N O3 SCYS
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free:  0.227 (Depositor), 0.239 (DCC) 
  • R-Value Work:  0.199 (Depositor), 0.210 (DCC) 
Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 60.087α = 90
b = 85.417β = 90
c = 135.662γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
DIALSdata reduction
Aimlessdata scaling
PHASERphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Biotechnology and Biological Sciences Research Council (BBSRC)United KingdomBB/X001032/1

Revision History  (Full details and data files)

  • Version 1.0: 2025-11-12
    Type: Initial release