1hm7
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(New page: 200px<br /><applet load="1hm7" size="450" color="white" frame="true" align="right" spinBox="true" caption="1hm7, resolution 2.9Å" /> '''N219L PENTALENENE SYN...)
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Revision as of 14:31, 20 November 2007
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N219L PENTALENENE SYNTHASE
Overview
Incubation of farnesyl diphosphate (1) with the W308F or W308F/H309F, mutants of pentalenene synthase, an enzyme from Streptomyces UC5319, yielded pentalenene (2), accompanied by varying proportions of, (+)-germacrene A (7) with relatively minor changes in k(cat) and, k(cat)/K(m). By contrast, single H309 mutants gave rise to both, (+)-germacrene A (7) and protoilludene (8) in addition to pentalenene (2)., Mutation to glutamate of each of the three aspartate residues in the, Mg(2+)-binding aspartate-rich domain, (80)DDLFD, resulted in reduction in, the k(cat)/K(m) for farnesyl diphosphate and formation of varying, proportions of pentalenene and (+)-germacrene A (7). Formation of, (+)-germacrene A (7) by the various pentalenene synthase mutants is the, result of a derailment of the natural anti-Markovnikov cyclization, reaction, and not simply the consequence of trapping of a normally, cryptic, carbocationic intermediate. Both the N219A and N219L mutants of, pentalenene synthase were completely inactive, while the corresponding, N219D mutant had a k(cat)/K(m) which was 3300-fold lower than that of the, wild-type synthase, and produced a mixture of pentalenene (2) (91%) and, the aberrant cyclization product beta-caryophyllene (9) (9%). Finally, the, F77Y mutant had a k(cat)/K(m) which was reduced by 20-fold compared to, that of the wild-type synthase.
About this Structure
1HM7 is a Single protein structure of sequence from Streptomyces sp.. Active as Pentalenene synthase, with EC number 4.2.3.7 Full crystallographic information is available from OCA.
Reference
Pentalenene synthase. Analysis of active site residues by site-directed mutagenesis., Seemann M, Zhai G, de Kraker JW, Paschall CM, Christianson DW, Cane DE, J Am Chem Soc. 2002 Jul 3;124(26):7681-9. PMID:12083921
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