A micromethod for the stereochemical analysis of fatty acid desaturase-mediated sulfoxidation reactions

Lao, Kim Y.Y.; Hodgson, Derek J.; Dawson, Brian; Buist, Peter H.

doi:10.1016/j.bmcl.2005.03.108

Cited by 8 publications

(7 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The combined organic phases were dried over Na 2 SO 4 and concentrated by roto-evaporation. The title compound was obtained by flash chromatography (60% EtOAc-hexanes) to obtain a white solid (0.27 g, 0.61 mmol, 80% (7), 89 (3), 75 (24), 69 (16), 55 (16), 41 (10).…”

Section: Tert-butyl-[10-(8-fluoro-octane-1-(s)-sulfinyl)-decyloxy]-di...mentioning

confidence: 99%

Stereochemistry of 10-sulfoxidation catalyzed by a soluble Δ9 desaturase

et al. 2010

Self Cite

View full text Add to dashboard Cite

The stereochemistry of castor stearoyl-ACP Delta(9) desaturase-mediated 10-sulfoxidation has been determined. This was accomplished by (19)F NMR analysis of a fluorine-tagged product, 18-fluoro-10-thiastearoyl ACP S-oxide, in combination with a chiral solvating agent, (R)-AMA. Sulfoxidation proceeds with the same stereoselectivity as hydrogen removal from the parent stearoyl substrate. These data validate the use of thia probes to determine the stereochemistry and cryptoregiochemistry of desaturase-mediated oxidations.

show abstract

Section: Tert-butyl-[10-(8-fluoro-octane-1-(s)-sulfinyl)-decyloxy]-di...mentioning

confidence: 99%

Stereochemistry of 10-sulfoxidation catalyzed by a soluble Δ9 desaturase

et al. 2010

Self Cite

View full text Add to dashboard Cite

show abstract

“…The stereochemistry of the desaturase-catalyzed oxidation of a fluorine-tagged thia fatty acid analogues can also be determined using chiral solvating agents in combination with 'H decoupled 19 F NMR spectroscopy. [22] The induced non-equivalence of the remote fluorine reporter group can be predicted based on the shielding effects anticipated in the collision complex of a CSA with the chiral sulfoxide using a Pirkle-type binding model (Figure 2.1). [17 ' 23] Spiking experiments with racemic sulfoxide mixtures are then used to provide a reference signal to allow the assignment of the stereochemistry of the product.…”

Section: Chiral Solvating Agents Applied To the Nmr Analysis Of Sulfoxidesmentioning

confidence: 99%

“…The aim of this part of the thesis was to test the validity of the Pirkle binding model in the stereochemical analysis of fluorinated sulfoxy fatty acid analogues using 19 planned to test the validity of the published results of K.Y.Y. Lao et al [22] in which the use 19 F NMR as a probe for the stereochemistry of the fatty acid desaturase-mediated sulfoxidation reactions was introduced. Finally, it was necessary to synthesize the chiral s agents (R)-and ( 5)-(9-anthryl)methoxyacetic acid (Figure 2.5 E and F) for use in the stereochemical analysis.…”

Section: Project Goalsmentioning

confidence: 99%

“…To be certain that the observed effects of the chiral shift agent were not attributable to the dilution of the sample, the effects of ( 5)-MPAA on the 19 F NMR shifts were measured at both a 15 millimolar and a 40 nanomolar scale, the latter corresponding to the conditions of the analysis of the biosynthetic product. [22] In both cases, 4 equivalents of ( 5)-MPAA was used and the volume of CDC1 3 was approximately 0.9 ml. The A5 S ' R for both dilutions was negative, confirming that concentration of analyte was not important with respect to the direction of induced-non equivalence in the 'H-decoupled 19 F NMR results.…”

Section: Investigation Of the Effect Of Dilution On The Direction Of Induced Non-equivalencementioning

confidence: 99%

“…This explanation would also account for the very low yield (<0.05%) and its low % ee (32%). [22] ppm enzymic B l(S) ,-,_,-i , | r , j , , ,-|…”

mentioning

confidence: 99%

See 2 more Smart Citations

Mechanistic studies of desaturase-mediated oxidations

Tremblay¹

View full text Add to dashboard Cite

The study of the mechanism of fatty acid desaturases often requires the use of synthetic probes and/or standards. In this work, a general procedure for preparing chiral fluorine-tagged dialkyl sulfoxides was developed using DAG methodology. 18-fluoro-(10S)sulfoxy-1-octadecanol, 18-fluoro-(10i?)-sulfoxy-l-octadecanol, 15-fluoro-(l 15)-sulfoxypentadecane, and 15-fluoro-(lli?)-sulfoxypentadecane were prepared. These standards were used in the determination of the stereochemistry of enzymatically produced sulfoxides arising from the introduction of fluorine-tagged thia fatty acid analogues to a soluble and a membrane-bound A 9 desaturase.In this study, it has been shown that the Pirkle binding model is successful for predicting the direction of induced non-equivalence of fluorine-tagged dialkyl sulfoxide enantiomers by ! H NMR using the chiral solvating agents AMA, MPAA and TFAE. However, the observed non-equivalence of 19 F NMR signals of these sulfoxides under similar conditions is dependent on the nature of the chiral reagent used.The identification of the products of a triple mutant, T117R/G188L/D280K of the castor A 9 desaturase was also undertaken using synthetic standards in combination with GC-MS. (10Z)-and (10£)-9-hydroxy-10-octadecenoate and (9Z)-and (9£)-ll-hydroxy-9octadecenoate were synthesized by known methods. The dienoic fatty acid esters, methyl 9Z,ll£'-octadecadienoate with a minor component of methyl 9is,ll£'-octadecadienoate were prepared in a 9:1 ratio and a mixture of 9Z,llZ-octadecadienoate and methyl 9£',11Zoctadecadienoate were also prepared. in Chemoselectivity 12Chapter 2: Results and Discussion 2.1 Determination of the enantioselectivity of soluble A 9 desaturase-mediated sulfoxidation using fluorine-tagged substrates 16 2.1.1 Introduction 16 V 2.1.1.1 Use of 'H-decoupled 19 F NMR in the study of desaturase-mediated oxidation 16 2.1.1.2 Efforts to determine the enantioselectivity of soluble A 9 desaturasemediated sulfoxidation \j 2.1.2 Project goals 20 2.1.3 Synthesis of fluorine-tagged chiral sulfoxide standards 21 2.1.3.1 Synthesis of (105)-and (107v)-18-fluoro-10-sulfoxy-l-octadecanol 26 2.1.3.2 Synthesis of (US)-and (117?)-15-fluoro-ll-sulfoxypentadecane 36 2.1.4 Synthesis of (R) and (S) (9-anthryl)methoxyacetic acid (AMA) 41 2.1.5 NMR experiments 45 2.1.5.1 Assignment of the absolute configuration of 18-fluoro-10-sulfoxy-loctadecanol produced by a soluble A 9 desaturase 45 2.1.5.2 Investigation of the role of the C1 hydroxyl group on the CSA induced NMR non-equivalences 48 2.1.5.3 Assignment of the absolute configuration of methyl 15-fluoro-l 1sulfoxypentadecanoate produced by growing S. cerevisae cultures 49 2.1.5.4 Investigation of the effect of dilution on the direction of induced non-equivalence 51 2.1.5.5 A study of the direction of induced non-equivalence in 'H and 'H-decoupled 19 F NMR for various chiral solvation reagents 52 2.1.6 Conclusions and future directions 55 2.2 Study of the catalytic diversity of an acyl-ACP desaturase mutant 57 2.2.1 Introduction 57 2.2.2 Project go...

show abstract

Fatty Acid Desaturases, Chemistry of

Buist

2008

Wiley Encyclopedia of Chemical Biology

View full text Add to dashboard Cite

The mid‐chain dehydrogenation of saturated fatty acyl derivatives is carried out by a large family of O 2 ‐dependent, nonheme diiron‐containing enzymes known as desaturases. Both soluble and membrane‐bound desaturases have been characterized. The mechanism of desaturation is thought to involve the stepwise syn removal of vicinal hydrogen atoms via a short‐lived carbon‐centered radical intermediate. The most common desaturase inserts a ( Z )‐double bond between the C9,10 carbons of a stearoyl thioester; however, many variations of this prototypical reaction have been discovered. Accounting for this diversity in terms of subtle alterations in active‐site architecture constitutes a new frontier for research in this area.

show abstract

A micromethod for the stereochemical analysis of fatty acid desaturase-mediated sulfoxidation reactions

Cited by 8 publications

References 19 publications

Stereochemistry of 10-sulfoxidation catalyzed by a soluble Δ9 desaturase

Stereochemistry of 10-sulfoxidation catalyzed by a soluble Δ9 desaturase

Mechanistic studies of desaturase-mediated oxidations

Fatty Acid Desaturases, Chemistry of

Contact Info

Product

Resources

About