Mle-Phe-Mle-Phe. Linear precursor of pseudoxylallemycin A.

Experimental Data Snapshot

  • Resolution: 0.83 Å
  • R-Value Observed: 0.068 

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Investigations of the key macrolactamisation step in the synthesis of cyclic tetrapeptide pseudoxylallemycin A.

Cameron, A.J.Squire, C.J.Gerenton, A.Stubbing, L.A.Harris, P.W.R.Brimble, M.A.

(2019) Org Biomol Chem 17: 3902-3913

  • DOI: https://doi.org/10.1039/c9ob00227h
  • Primary Citation of Related Structures:  
    6MVZ, 6MW0, 6MW1, 6MW2

  • PubMed Abstract: 

    The total synthesis and structural confirmation of naturally occurring all l-cyclic tetrapeptide pseudoxylallemycin A is reported. X-ray crystallography revealed that the linear precursor adopted an all-trans (ttt) extended linear conformation, while its cyclic derivative adopts a trans,cis,trans,cis (tctc) conformation. Two kinetically favoured cyclic conformers prone to hydrolysis initially formed rapidly during cyclisation, with subsequent conversion to the thermodynamically stable tctc macrocycle taking place slowly. We postulate the initial unstable cyclic product undergoes an unprecedented nucleophilic ring opening with either the T3P or PyAOP by-products to give the linear ttt structure as a reactivated species and through a series of equilibria is slowly consumed by cyclisation to the thermodynamic product pseudoxylallemycin A. Consumption of the reactivated species by formation of pseudoxylallemycin A requires a trans-cis isomerism to occur and necessitates moderately increased reaction temperatures. Cyclisation with T3P was found to provide the greatest stereoretention. Synthesis and X-ray crystallography of the C-terminal epimer demonstrated its cyclisation to be kinetically favoured and to proceed without epimerisation despite also bearing an all-trans backbone.

  • Organizational Affiliation

    School of Chemical Sciences, The University of Auckland, 23 Symonds St, Auckland 1010, New Zealand. m.brimble@auckland.ac.nz.


Find similar proteins by:  Sequence   |   3D Structure  

Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Linear precursor of pseudoxylallemycin A4XylariaMutation(s): 0 
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on TFA

Download Ideal Coordinates CCD File 
B [auth A]trifluoroacetic acid
C2 H F3 O2
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
Query on MLE
Biologically Interesting Molecules (External Reference) 1 Unique
Experimental Data & Validation

Experimental Data

  • Resolution: 0.83 Å
  • R-Value Observed: 0.068 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 8.255α = 90
b = 19.173β = 90
c = 23.446γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
Aimlessdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2019-09-11
    Type: Initial release