The stereochemistry of hydrogen elimination from C-7 in cholesterol and ergosterol biosynthesis

Akhtar, Muhammad; Rahimtula, Anver D.; Wilton, David C.

doi:10.1042/bj1170539

Cited by 24 publications

(22 citation statements)

References 16 publications

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“…Abbreviations used : gCOSY, gradient COSY ; gHSQC, gradient heteronuclear single-quantum coherence ; GPC, gel-permeation column ; HEI, highenergy intermediate ; HMBC, heteronuclear multiple bond correlation ; hSI, human sterol 8-isomerase ; MALDI-TOF MS, matrix-assisted laser-desorption ionization-time-of-flight MS ; PEG, poly(ethylene glycol) ; RRT c , retention time of compound relative to the retention time of cholesterol. 1 To whom correspondence should be addressed (e-mail wdavid.nes!ttu.edu).…”

Section: Figure 1 Hypothetical Pathway Of Lanosterol Conversion To Chmentioning

confidence: 99%

“…Under normal metabolic conditions structure 5 (see Figure 1) is isomerized to structure 6. The model for enzyme-mediated 8-to-7 isomerization predicts electrophilic attack of a proton associated with an active-site amino acid on a sterol substrate that results in the formation of a cationic high-energy intermediate (HEI) at C-8 [1,3]. During the reaction a proton derived ultimately from water (H w ) is added axial to the C-C double bond at C-9, and carbon-bound equatorial 7β hydrogen is eliminated to water.…”

Section: Figure 1 Hypothetical Pathway Of Lanosterol Conversion To Chmentioning

confidence: 99%

“…The transformation of lanosterol to cholesterol involves the rearrangement of the 8(9)-double bond [1,2]. Human sterol 8-isomerase (hSI ; EC 5.3.3.5 ; also known as emopamil-binding protein) is considered to catalyse the interconversion of the ∆)-…”

Section: Introductionmentioning

confidence: 99%

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Purification, characterization and catalytic properties of human sterol 8-isomerase

Nes

Zhou

Dennis

et al. 2002

Biochemical Journal

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CHO 2, encoding human sterol 8-isomerase (hSI), was introduced into plasmids pYX213 or pET23a. The resulting native protein was overexpressed in erg 2 yeast cells and purified to apparent homogeneity. The enzyme exhibited a K (m) of 50 microM and a turnover number of 0.423 s(-1) for zymosterol, an isoelectric point of 7.70, a native molecular mass of 107000 Da and was tetrameric. The structural features of zymosterol provided optimal substrate acceptability. Biomimetic studies of acid-catalysed isomerization of zymosterol resulted in formation of cholest-8(14)-enol, whereas the enzyme-generated product was a Delta(7)-sterol, suggesting absolute stereochemical control of the reaction by hSI. Using (2)H(2)O and either zymosterol or cholesta-7,24-dienol as substrates, the reversibility of the reaction was confirmed by GC-MS of the deuterated products. The positional specific incorporation of deuterium at C-9alpha was established by a combination of (1)H- and (13)C-NMR analyses of the enzyme-generated cholesta-7,24-dienol. Kinetic analyses indicated the reaction equilibrium ( K (eq)=14; DeltaG(o')=-6.5 kJ/mol) for double-bond isomerization favoured the forward direction, Delta(8) to Delta(7). Treatment of hSI with different high-energy intermediate analogues produced the following dissociation constants ( K (i)): emopamil (2 microM)=tamoxifen (1 microM)=tridemorph (1 microM)<25-azacholesterol (21 microM)

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Section: Figure 1 Hypothetical Pathway Of Lanosterol Conversion To Chmentioning

confidence: 99%

Section: Figure 1 Hypothetical Pathway Of Lanosterol Conversion To Chmentioning

confidence: 99%

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Purification, characterization and catalytic properties of human sterol 8-isomerase

Nes

Zhou

Dennis

et al. 2002

Biochemical Journal

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“…The reduction of the A 14 double bond is assumed to be initiated by a protonation step at C15 (see Fig. 2) [34]. The intermediate allyl carbocation is mesomerically stabilized.…”

Section: Inhibitors Of Ergosterol Biosynthesismentioning

confidence: 99%

Different approaches toward an automatic structural alignment of drug molecules: Applications to sterol mimics, thrombin and thermolysin inhibitors

Klebe

Mietzner

Weber

1994

J Computer-Aided Mol Des

108

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A relative comparison of the binding properties of different drug molecules requires their mutual superposition with respect to various alignment criteria. In order to validate the results of different alignment methods, the crystallographically observed binding geometries of ligands in the pocket of a common protein receptor have been used. The alignment function in the program SEAL that calculates the mutual superposition of molecules has been optimized with respect to these references. Across the reference data set, alignments could be produced that show mean rms deviations of approximately 1 A compared to the experimental situation. For structures with obvious skeletal similarities a multiple-flexible fit, linking common pharmacophoric groups by virtual springs, has been incorporated into the molecular mechanics program MOMO. In order to combine conformational searching with comparative alignments, the optimized SEAL approach has been applied to sets of conformers generated by MIMUMBA, a program for conformational analysis. Multiple-flexible fits have been calculated for inhibitors of ergosterol biosynthesis. Sets of different thrombin and thermolysin inhibitors have been conformationally analyzed and subsequently aligned by a combined MIMUMBA/SEAL approach. Since for these examples crystallographic data on their mutual alignment are available, an objective assessment of the computed results could be performed. Among the generated conformers, one geometry could be selected for the thrombin and thermolysin inhibitors that approached reasonably well the experimentally observed alignment.

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“…We have established that both steps in the reduction of 3-hydroxy-3-methylglutaryl-CoA (11) to mevalonic acid (IV) catalysed by rat liver 3-hydroxy- We thank Dr M. Akhtar for many helpful dmcussions.…”

Section: Discussionmentioning

confidence: 99%

The Stereochemistry of Hydrogen Transfer from NADPH Catalysed by 3‐Hydroxy‐3‐methylglutaryl‐coenzyme A Reductase from Rat Liver

Beedle

Munday

Wilton

1972

European Journal of Biochemistry

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The resulting doubly labelled mevalonic acid incorporated tritium exclusively from the 4A (4R) position of NADPH. The distribution of tritium a t C-5 of the mevalonic acid was determined by a biological degradation. It was concluded that during the reduction of 3-hydroxy-3-methylglutaryl-CoA to mevalonic acid two hydrogen atoms from the 4A (4R) position of NADPH are transferred directly to mevalonic acid.The enzyme 3-hydroxy-3-methylglutaryl-CoA

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The stereochemistry of hydrogen elimination from C-7 in cholesterol and ergosterol biosynthesis

Cited by 24 publications

References 16 publications

Purification, characterization and catalytic properties of human sterol 8-isomerase

Purification, characterization and catalytic properties of human sterol 8-isomerase

Different approaches toward an automatic structural alignment of drug molecules: Applications to sterol mimics, thrombin and thermolysin inhibitors

The Stereochemistry of Hydrogen Transfer from NADPH Catalysed by 3‐Hydroxy‐3‐methylglutaryl‐coenzyme A Reductase from Rat Liver

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