1fgo
From Proteopedia
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LIPOXYGENASE-1 (SOYBEAN) AT 100K, Q495A MUTANT
Overview
Lipoxygenases are an important class of non-heme iron enzymes that, catalyze the hydroperoxidation of unsaturated fatty acids. The details of, the enzymatic mechanism of lipoxygenases are still not well understood., This study utilizes a combination of kinetic and structural probes to, relate the lipoxygenase mechanism of action with structural modifications, of the iron's second coordination sphere. The second coordination sphere, consists of Gln(495) and Gln(697), which form a hydrogen bond network, between the substrate cavity and the first coordination sphere (Asn(694))., In this investigation, we compared the kinetic and structural properties, of four mutants (Q495E, Q495A, Q697N, and Q697E) with those of wild-type, soybean lipoxygenase-1 and determined that changes in the second, coordination sphere affected the enzymatic activity by hydrogen bond, rearrangement and substrate positioning through interaction with Gln(495)., The nature of the C-H bond cleavage event remained unchanged, which, demonstrates that the mutations have not affected the mechanism of, hydrogen atom tunneling. The unusual and dramatic inverse solvent isotope, effect (SIE) observed for the Q697E mutant indicated that an Fe(III)-OH(-), is the active site base. A new transition state model for hydrogen atom, abstraction is proposed.
About this Structure
1FGO is a Single protein structure of sequence from Glycine max with FE as ligand. Active as Lipoxygenase, with EC number 1.13.11.12 Full crystallographic information is available from OCA.
Reference
Structural and functional characterization of second-coordination sphere mutants of soybean lipoxygenase-1., Tomchick DR, Phan P, Cymborowski M, Minor W, Holman TR, Biochemistry. 2001 Jun 26;40(25):7509-17. PMID:11412104
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