Interactions of Isopenicillin N Synthase with Cyclopropyl-Containing Substrate Analogues Reveal New Mechanistic Insight
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- 作者：Annaleise R. Howard-Jones ; Jonathan M. Elkins ; Ian J. Clifton ; Peter L. Roach ; Robert M. Adlington ; Jack E. Baldwin ; Peter J. Rutledge
- 刊名：Biochemistry
- 出版年：2007
- 出版时间：April 24, 2007
- 年：2007
- 卷：46
- 期：16
- 页码：4755 - 4762
- 全文大小：473K
- 年卷期：v.46,no.16(April 24, 2007)
- ISSN：1520-4995
文摘
Isopenicillin N synthase (IPNS), a non-heme iron oxidase central to penicillin and cephalosporinbiosynthesis, catalyzes an energetically demanding chemical transformation to produce isopenicillin Nfrom the tripeptide 
ta.gif" BORDER=0 >-(L-
-aminoadipoyl)-L-cysteinyl-D-valine (ACV). We describe the synthesis of twocyclopropyl-containing tripeptide analogues, ta.gif" BORDER=0 >-(L--aminoadipoyl)-L-cysteinyl-
ta2.gif" BORDER=0 ALIGN="middle">-methyl-D-cyclopropylglycine and ta.gif" BORDER=0 >-(L--aminoadipoyl)-L-cysteinyl-D-cyclopropylglycine, designed as probes for the mechanismof IPNS. We have solved the X-ray crystal structures of these substrates in complex with IPNS andpropose a revised mechanism for the IPNS-mediated turnover of these compounds. Relative to the previouslydetermined IPNS-Fe(II)-ACV structure, key differences exist in substrate orientation and water occupancy,which allow for an explanation of the differences in reactivity of these substrates.
ta.gif" BORDER=0 >-(L--aminoadipoyl)-L-cysteinyl-D-valine (ACV). We describe the synthesis of twocyclopropyl-containing tripeptide analogues, ta.gif" BORDER=0 >-(L--aminoadipoyl)-L-cysteinyl-ta2.gif" BORDER=0 ALIGN="middle">-methyl-D-cyclopropylglycine and ta.gif" BORDER=0 >-(L--aminoadipoyl)-L-cysteinyl-D-cyclopropylglycine, designed as probes for the mechanismof IPNS. We have solved the X-ray crystal structures of these substrates in complex with IPNS andpropose a revised mechanism for the IPNS-mediated turnover of these compounds. Relative to the previouslydetermined IPNS-Fe(II)-ACV structure, key differences exist in substrate orientation and water occupancy,which allow for an explanation of the differences in reactivity of these substrates.