Mechanism-based active site modification of the soybean sterol methyltransferase by 26,27-dehydrocycloartenol

Zhihong Song; Wenxu Zhou; Jialin Liu; W. David Nes

doi:10.1016/j.bmcl.2003.10.015

Mechanism-based active site modification of the soybean sterol methyltransferase by 26,27-dehydrocycloartenol

Zhihong Song, Wenxu Zhou, Jialin Liu, W. David Nes

Chemistry and Biochemistry

Research output: Contribution to journal › Article › peer-review

9 Scopus citations

Abstract

26,27-Dehydrocycloartenol (26,27-DHC) was shown to be a substrate for the soybean sterol methyltransferase (SMT) as well as a mechanism-based inhibitor of enzyme action. The K_m and k_cat for 26,27-DHC was 10 μM and 0.018 min^-1, respectively. SMT catalyzed 26,27-DHC to two products tentatively identified as 26-homocholesta-9,19-cyclo-23(24)E, 26(26′)-dienol and 26-homocholesta-9,19-cyclo-26(26′)-en-3β, 24β-diol by GC-MS. Inhibitor treatment was concentration- and time-dependent (pseudo-first-order kinetics). A replot of the half-lives for inactivation versus the inverse of the inactivator concentrations gave an apparent K_i of 42 μM and a maximum rate of inactivation of 0.29 min^-1. A partition ratio (k_cat/k_inact) was calculated to be 0.06.

Original language	English
Pages (from-to)	33-36
Number of pages	4
Journal	Bioorganic and Medicinal Chemistry Letters
Volume	14
Issue number	1
DOIs	https://doi.org/10.1016/j.bmcl.2003.10.015
State	Published - Jan 5 2004

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@article{6f4a8737432342a5b7b60a59cec68fa6,

title = "Mechanism-based active site modification of the soybean sterol methyltransferase by 26,27-dehydrocycloartenol",

abstract = "26,27-Dehydrocycloartenol (26,27-DHC) was shown to be a substrate for the soybean sterol methyltransferase (SMT) as well as a mechanism-based inhibitor of enzyme action. The Km and kcat for 26,27-DHC was 10 μM and 0.018 min-1, respectively. SMT catalyzed 26,27-DHC to two products tentatively identified as 26-homocholesta-9,19-cyclo-23(24)E, 26(26′)-dienol and 26-homocholesta-9,19-cyclo-26(26′)-en-3β, 24β-diol by GC-MS. Inhibitor treatment was concentration- and time-dependent (pseudo-first-order kinetics). A replot of the half-lives for inactivation versus the inverse of the inactivator concentrations gave an apparent Ki of 42 μM and a maximum rate of inactivation of 0.29 min-1. A partition ratio (kcat/kinact) was calculated to be 0.06.",

author = "Zhihong Song and Wenxu Zhou and Jialin Liu and Nes, {W. David}",

year = "2004",

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day = "5",

doi = "10.1016/j.bmcl.2003.10.015",

language = "English",

volume = "14",

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journal = "Bioorganic and Medicinal Chemistry Letters",

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T1 - Mechanism-based active site modification of the soybean sterol methyltransferase by 26,27-dehydrocycloartenol

AU - Song, Zhihong

AU - Zhou, Wenxu

AU - Liu, Jialin

AU - Nes, W. David

PY - 2004/1/5

Y1 - 2004/1/5

N2 - 26,27-Dehydrocycloartenol (26,27-DHC) was shown to be a substrate for the soybean sterol methyltransferase (SMT) as well as a mechanism-based inhibitor of enzyme action. The Km and kcat for 26,27-DHC was 10 μM and 0.018 min-1, respectively. SMT catalyzed 26,27-DHC to two products tentatively identified as 26-homocholesta-9,19-cyclo-23(24)E, 26(26′)-dienol and 26-homocholesta-9,19-cyclo-26(26′)-en-3β, 24β-diol by GC-MS. Inhibitor treatment was concentration- and time-dependent (pseudo-first-order kinetics). A replot of the half-lives for inactivation versus the inverse of the inactivator concentrations gave an apparent Ki of 42 μM and a maximum rate of inactivation of 0.29 min-1. A partition ratio (kcat/kinact) was calculated to be 0.06.

AB - 26,27-Dehydrocycloartenol (26,27-DHC) was shown to be a substrate for the soybean sterol methyltransferase (SMT) as well as a mechanism-based inhibitor of enzyme action. The Km and kcat for 26,27-DHC was 10 μM and 0.018 min-1, respectively. SMT catalyzed 26,27-DHC to two products tentatively identified as 26-homocholesta-9,19-cyclo-23(24)E, 26(26′)-dienol and 26-homocholesta-9,19-cyclo-26(26′)-en-3β, 24β-diol by GC-MS. Inhibitor treatment was concentration- and time-dependent (pseudo-first-order kinetics). A replot of the half-lives for inactivation versus the inverse of the inactivator concentrations gave an apparent Ki of 42 μM and a maximum rate of inactivation of 0.29 min-1. A partition ratio (kcat/kinact) was calculated to be 0.06.

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DO - 10.1016/j.bmcl.2003.10.015

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JO - Bioorganic and Medicinal Chemistry Letters

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