1odm
From Proteopedia
ISOPENICILLIN N SYNTHASE FROM ASPERGILLUS NIDULANS (ANAEROBIC AC-VINYLGLYCINE FE COMPLEX)
Overview
Isopenicillin N synthase (IPNS) catalyses conversion of the linear tripeptide delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-valine (ACV) to isopenicillin N (IPN), the central step in biosynthesis of the beta-lactam antibiotics. The unsaturated substrate analogue delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-vinylglycine (ACvG) has previously been incubated with IPNS and single product was isolated, a 2-alpha-hydroxymethyl isopenicillin N (HMPen), formed via a monooxygenase mode of reactivity. ACvG has now been crystallised with IPNS and the structure of the anaerobic IPNS:Fe(II):ACvG complex determined to 1.15 A resolution. Furthermore, by exposing the anaerobically grown crystals to high-pressure oxygen gas, a structure corresponding to the bicyclic product HMPen has been obtained at 1.60 A resolution. In light of these and other IPNS structures, and recent developments with related dioxygenases, the [2 + 2] cycloaddition mechanism for HMPen formation from ACvG has been revised, and a stepwise radical mechanism is proposed. This revised mechanism remains consistent with the observed stereospecificity of the transformation, but fits better with apparent constraints on the coordination geometry around the active site iron atom.
About this Structure
1ODM is a Single protein structure of sequence from Emericella nidulans. Full crystallographic information is available from OCA.
Reference
Crystallographic studies on the reaction of isopenicillin N synthase with an unsaturated substrate analogue., Elkins JM, Rutledge PJ, Burzlaff NI, Clifton IJ, Adlington RM, Roach PL, Baldwin JE, Org Biomol Chem. 2003 May 7;1(9):1455-60. PMID:12926272 Page seeded by OCA on Sat May 3 03:42:44 2008
