1C1S

RECRUITING ZINC TO MEDIATE POTENT, SPECIFIC INHIBITION OF SERINE PROTEASES


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.63 Å
  • R-Value Free: 0.206 
  • R-Value Work: 0.185 
  • R-Value Observed: 0.185 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Recruiting Zn2+ to mediate potent, specific inhibition of serine proteases.

Katz, B.A.Luong, C.

(1999) J Mol Biol 292: 669-684

  • DOI: 10.1006/jmbi.1999.3071
  • Primary Citation of Related Structures:  
    1C1S

  • PubMed Abstract: 
  • As regulators of ubiquitous biological processes, serine proteases can cause disease states when inappropriately expressed or regulated, and are thus rational targets for inhibition by drugs. Recently we described a new inhibition mechanism applicabl ...

    As regulators of ubiquitous biological processes, serine proteases can cause disease states when inappropriately expressed or regulated, and are thus rational targets for inhibition by drugs. Recently we described a new inhibition mechanism applicable for the development of potent, selective small molecule serine protease inhibitors that recruit physiological Zn2+ to mediate high affinity (sub-nanomolar) binding. To demonstrate some of the structural principles by which the selectivity of Zn2+-mediated serine protease inhibitors can be developed toward or against a particular target, here we determine and describe the structures of thrombin-BABIM-Zn2+, -keto-BABIM-Zn2+, and -hemi-BABIM-Zn2+ (where BABIM is bis(5-amidino-2-benzimidazolyl)methane, keto-BABIM is bis(5-amidino-2-benzimidazolyl)methane ketone, and hemi-BABIM is (5-amidino-2-benzimidazolyl)(2-benzimidazolyl)methane), and compare them with the corresponding trypsin-inhibitor-Zn2+ complexes. Inhibitor binding is mediated by a Zn ion tetrahedrally coordinated by two benzimidazole nitrogen atoms of the inhibitor, by N(epsilon2)His57, and by O(gamma)Ser195. The structures of Zn2+-free trypsin-BABIM and -hemi-BABIM were also determined at selected pH values for comparison with the corresponding Zn2+-mediated complexes. To assess some of the physiological parameters important for harnessing Zn2+ as a co-inhibitor, crystal structures at multiple pH and [Zn2+] values were determined for trypsin-keto-BABIM. The Kdvalue of Zn2+ for the binary trypsin-keto-BABIM complex was estimated to be <12 nM at pH 7.06 by crystallographic determination of the occupancy of bound Zn2+ in trypsin-keto-BABIM crystals soaked at this pH in synthetic mother liquor containing inhibitor and 100 nM Zn2+. In synthetic mother liquor saturated in Zn2+, trypsin-bound keto-BABIM is unhydrated at pH 9.00 and 9.93, and has an sp2 hybridized ketone carbon bridging the 5-amidinobenzimidazoles, whereas at pH 7.00 and 8.00 it undergoes hydration and a change in geometry upon addition of water to the bridging carbonyl group. To show how Zn2+ could be recruited as a co-inhibitor of other enzymes, a method was developed for locating in protein crystals Zn2+ binding sites where design of Zn2+-mediated ligands can be attempted. Thus, by soaking trypsin crystals in high concentrations of Zn2+ in the absence of a molecular inhibitor, the site where Zn2+ mediates binding of BABIM and analogs was identified, as well as another Zn2+ binding site.


    Organizational Affiliation

    Axys Pharmaceutical Corporation, 385 Oyster Point Boulevard, South San Francisco, CA 94080, USA. bak@axyspharm.com



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
TRYPSINA223Bos taurusMutation(s): 0 
EC: 3.4.21.4
Find proteins for P00760 (Bos taurus)
Explore P00760 
Go to UniProtKB:  P00760
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
BAB
Query on BAB

Download CCD File 
A
BIS(5-AMIDINO-BENZIMIDAZOLYL)METHANE
C17 H19 N8
QZKOOEFIMWKZPK-UHFFFAOYSA-Q
 Ligand Interaction
PO4
Query on PO4

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A
PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
 Ligand Interaction
CA
Query on CA

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A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
NA
Query on NA

Download CCD File 
A
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.63 Å
  • R-Value Free: 0.206 
  • R-Value Work: 0.185 
  • R-Value Observed: 0.185 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 55.35α = 90
b = 55.35β = 90
c = 109.8γ = 120
Software Package:
Software NamePurpose
bioteXdata collection
bioteXdata reduction
X-PLORmodel building
Quantamodel building
Insight IImodel building
X-PLORrefinement
bioteXdata scaling
X-PLORphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

  • Deposited Date: 1999-07-21 
  • Released Date: 2000-07-26 
  • Deposition Author(s): Katz, B.A., Luong, C.

Revision History 

  • Version 1.0: 2000-07-26
    Type: Initial release
  • Version 1.1: 2007-10-23
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Atomic model, Version format compliance
  • Version 1.3: 2017-10-04
    Changes: Advisory, Refinement description