3E8L

The Crystal Structure of the Double-headed Arrowhead Protease Inhibitor A in Complex with Two Trypsins


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.48 Å
  • R-Value Free: 0.245 
  • R-Value Work: 0.194 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

The ternary structure of double-headed arrowhead protease inhibitor API-A complexed with two trypsins reveals a novel reactive site conformation.

Bao, R.Zhou, C.Z.Jiang, C.-H.Lin, S.X.Chi, C.W.Chen, Y.X.

(2009) J.Biol.Chem. 284: 26676-26684

  • DOI: 10.1074/jbc.M109.022095

  • PubMed Abstract: 
  • The double-headed arrowhead protease inhibitors API-A and -B from the tubers of Sagittaria sagittifolia (Linn) feature two distinct reactive sites, unlike other members of their family. Although the two inhibitors have been extensively characterized, ...

    The double-headed arrowhead protease inhibitors API-A and -B from the tubers of Sagittaria sagittifolia (Linn) feature two distinct reactive sites, unlike other members of their family. Although the two inhibitors have been extensively characterized, the identities of the two P1 residues in both API-A and -B remain controversial. The crystal structure of a ternary complex at 2.48 A resolution revealed that the two trypsins bind on opposite sides of API-A and are 34 A apart. The overall fold of API-A belongs to the beta-trefoil fold and resembles that of the soybean Kunitz-type trypsin inhibitors. The two P1 residues were unambiguously assigned as Leu(87) and Lys(145), and their identities were further confirmed by site-directed mutagenesis. Reactive site 1, composed of residues P5 Met(83) to P5' Ala(92), adopts a novel conformation with the Leu(87) completely embedded in the S1 pocket even though it is an unfavorable P1 residue for trypsin. Reactive site 2, consisting of residues P5 Cys(141) to P5' Glu(150), binds trypsin in the classic mode by employing a two-disulfide-bonded loop. Analysis of the two binding interfaces sheds light on atomic details of the inhibitor specificity and also promises potential improvements in enzyme activity by engineering of the reactive sites.


    Organizational Affiliation

    Institute of Protein Research, Tongji University, Shanghai, China.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Serine proteinase inhibitor A
C
185Sagittaria sagittifoliaMutation(s): 2 
Find proteins for Q7M1P4 (Sagittaria sagittifolia)
Go to UniProtKB:  Q7M1P4
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Cationic trypsin
A, B
223Bos taurusMutation(s): 0 
EC: 3.4.21.4
Find proteins for P00760 (Bos taurus)
Go to UniProtKB:  P00760
Small Molecules
Ligands 7 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NA
Query on NA

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Download CCD File 
A
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
SO4
Query on SO4

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Download CCD File 
A, C
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
ACT
Query on ACT

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A, B, C
ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M
 Ligand Interaction
GOL
Query on GOL

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Download CCD File 
A, B, C
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
CA
Query on CA

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A, B
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
EDO
Query on EDO

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B
1,2-ETHANEDIOL
ETHYLENE GLYCOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
 Ligand Interaction
PEG
Query on PEG

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Download CCD File 
B
DI(HYDROXYETHYL)ETHER
C4 H10 O3
MTHSVFCYNBDYFN-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.48 Å
  • R-Value Free: 0.245 
  • R-Value Work: 0.194 
  • Space Group: C 2 2 21
Unit Cell:
Length (Å)Angle (°)
a = 76.634α = 90.00
b = 110.863β = 90.00
c = 152.991γ = 90.00
Software Package:
Software NamePurpose
SCALAdata scaling
MAR345dtbdata collection
PHASESphasing
REFMACrefinement
AUTOMARdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2009-07-28
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Advisory, Version format compliance
  • Version 1.2: 2013-09-18
    Type: Database references, Derived calculations