9RBL | pdb_00009rbl

Three dimensional structure of human carbonic anhydrase IX in complex with sulfonamide MKV558


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.05 Å
  • R-Value Free: 
    0.214 (Depositor), 0.221 (DCC) 
  • R-Value Work: 
    0.178 (Depositor), 0.187 (DCC) 
  • R-Value Observed: 
    0.180 (Depositor) 

Starting Model: experimental
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wwPDB Validation 3D Report Full Report

Validation slider image for 9RBL

Ligand Structure Quality Assessment 


This is version 1.0 of the entry. See complete history

Literature

Achieving femtomolar affinities in structure-based drug design.

Zubriene, A.Kurtenoka, M.Paketuryte-Latve, V.Leitans, J.Manakova, E.Zvirblis, M.Kazaks, A.Eimonta, V.Tars, K.Grazulis, S.Petrauskas, V.Matuliene, J.Dudutiene, V.Shubin, K.Matulis, D.

(2026) Eur Biophys J 55: 55-62

  • DOI: https://doi.org/10.1007/s00249-025-01812-5
  • Primary Citation Related Structures: 
    9RBL, 9RBM

  • PubMed Abstract: 

    Developing small-molecule compounds as effective and safe pharmaceuticals relies on their ability to bind disease-associated proteins with high affinity and selectivity. However, achieving ultra-high affinity in the femtomolar range is a major challenge in medicinal chemistry due to the inherent constraints of protein-ligand interactions. Here, we introduce a novel class of di-meta-substituted fluorinated benzenesulfonamide compounds that achieve an extraordinary dissociation constant of 44 fM for carbonic anhydrase IX (CAIX). CAIX, a transmembrane enzyme implicated in hypoxic tumor progression through the increase of microenvironment acidity, represents a promising target for anticancer therapy. Inhibiting CAIX may help suppress tumor growth and improve cancer treatment outcomes. The newly developed compounds exhibit the highest affinity for CAIX reported to date and rank among the strongest known non-covalent small-molecule inhibitors.


  • Organizational Affiliation
    • Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio 7, Vilnius, LT-10257, Lithuania.

Macromolecule Content 

  • Total Structure Weight: 114.56 kDa 
  • Atom Count: 7,866 
  • Modeled Residue Count: 956 
  • Deposited Residue Count: 1,024 
  • Unique protein chains: 1

Macromolecules

Find similar proteins by:|  3D Structure
Entity ID: 1
MoleculeChains  Sequence LengthOrganismDetailsImage
Carbonic anhydrase 9
A, B, C, D
256Homo sapiensMutation(s): 2 
Gene Names: CA9G250MN
EC: 4.2.1.1
UniProt & NIH Common Fund Data Resources
Find proteins for Q16790 (Homo sapiens)
Explore Q16790 
Go to UniProtKB:  Q16790
PHAROS:  Q16790
GTEx:  ENSG00000107159 
Entity Groups
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ16790
Sequence Annotations
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Reference Sequence

Small Molecules

Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
A1H92
(Subject of Investigation/LOI)

Query on A1H92



Download:Ideal Coordinates CCD File
F [auth A],
H [auth B],
J [auth C],
L [auth D]
3-(Cyclooctylamino)-5-ethoxy-2,6-difluoro-4-((3-hydroxypropyl)sulfonyl)benzenesulfonamide
C19 H30 F2 N2 O6 S2
HVTLSUDQRPQLKK-UHFFFAOYSA-N
ZN

Query on ZN



Download:Ideal Coordinates CCD File
E [auth A],
G [auth B],
I [auth C],
K [auth D]
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.05 Å
  • R-Value Free:  0.214 (Depositor), 0.221 (DCC) 
  • R-Value Work:  0.178 (Depositor), 0.187 (DCC) 
  • R-Value Observed: 0.180 (Depositor) 
Space Group: H 3
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 152.362α = 90
b = 152.362β = 90
c = 172.445γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
PDB_EXTRACTdata extraction
Aimlessdata scaling
MOLREPphasing

Structure Validation

View Full Validation Report



Ligand Structure Quality Assessment 


Entry History 

& Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
European Union (EU)European Union5.2.1.1.i.0/2/24/I/CFLA/001

Revision History  (Full details and data files)

  • Version 1.0: 2026-05-27
    Type: Initial release