Mechanistic evidence for a front-side, SNi-type reaction in a retaining glycosyltransferase.
A previously determined crystal structure of the ternary complex of trehalose-6-phosphate synthase identified a putative transition state-like arrangement based on validoxylamine A 6'-O-phosphate and uridine diphosphate in the active site. Here linear free energy relationships confirm that thes...
| Main Authors: | , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2011
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| _version_ | 1797098645752905728 |
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| author | Lee, S Hong, S Errey, J Izumi, A Davies, G Davis, B |
| author_facet | Lee, S Hong, S Errey, J Izumi, A Davies, G Davis, B |
| author_sort | Lee, S |
| collection | OXFORD |
| description | A previously determined crystal structure of the ternary complex of trehalose-6-phosphate synthase identified a putative transition state-like arrangement based on validoxylamine A 6'-O-phosphate and uridine diphosphate in the active site. Here linear free energy relationships confirm that these inhibitors are synergistic transition state mimics, supporting front-face nucleophilic attack involving hydrogen bonding between leaving group and nucleophile. Kinetic isotope effects indicate a highly dissociative oxocarbenium ion-like transition state. Leaving group (18)O effects identified isotopically sensitive bond cleavages and support the existence of a hydrogen bond between the nucleophile and departing group. Brønsted analysis of nucleophiles and Taft analysis highlight participation of the nucleophile in the transition state, also consistent with a front-face mechanism. Together, these comprehensive, quantitative data substantiate this unusual enzymatic reaction mechanism. Its discovery should prompt useful reassessment of many biocatalysts and their substrates and inhibitors. |
| first_indexed | 2024-03-07T05:12:36Z |
| format | Journal article |
| id | oxford-uuid:dc128fca-f331-4686-81ba-9ad54800e838 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T05:12:36Z |
| publishDate | 2011 |
| record_format | dspace |
| spelling | oxford-uuid:dc128fca-f331-4686-81ba-9ad54800e8382022-03-27T09:15:10ZMechanistic evidence for a front-side, SNi-type reaction in a retaining glycosyltransferase.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:dc128fca-f331-4686-81ba-9ad54800e838EnglishSymplectic Elements at Oxford2011Lee, SHong, SErrey, JIzumi, ADavies, GDavis, BA previously determined crystal structure of the ternary complex of trehalose-6-phosphate synthase identified a putative transition state-like arrangement based on validoxylamine A 6'-O-phosphate and uridine diphosphate in the active site. Here linear free energy relationships confirm that these inhibitors are synergistic transition state mimics, supporting front-face nucleophilic attack involving hydrogen bonding between leaving group and nucleophile. Kinetic isotope effects indicate a highly dissociative oxocarbenium ion-like transition state. Leaving group (18)O effects identified isotopically sensitive bond cleavages and support the existence of a hydrogen bond between the nucleophile and departing group. Brønsted analysis of nucleophiles and Taft analysis highlight participation of the nucleophile in the transition state, also consistent with a front-face mechanism. Together, these comprehensive, quantitative data substantiate this unusual enzymatic reaction mechanism. Its discovery should prompt useful reassessment of many biocatalysts and their substrates and inhibitors. |
| spellingShingle | Lee, S Hong, S Errey, J Izumi, A Davies, G Davis, B Mechanistic evidence for a front-side, SNi-type reaction in a retaining glycosyltransferase. |
| title | Mechanistic evidence for a front-side, SNi-type reaction in a retaining glycosyltransferase. |
| title_full | Mechanistic evidence for a front-side, SNi-type reaction in a retaining glycosyltransferase. |
| title_fullStr | Mechanistic evidence for a front-side, SNi-type reaction in a retaining glycosyltransferase. |
| title_full_unstemmed | Mechanistic evidence for a front-side, SNi-type reaction in a retaining glycosyltransferase. |
| title_short | Mechanistic evidence for a front-side, SNi-type reaction in a retaining glycosyltransferase. |
| title_sort | mechanistic evidence for a front side sni type reaction in a retaining glycosyltransferase |
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