- Stereo- and regiospecificity of yeast phytases-chemical synthesis and enzymatic conversion of the substrate analogues neo- and L-chiro-inositol hexakisphosphate
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Phytases are enzymes that catalyze the hydrolysis of phosphate esters in myo-inositol hexakisphosphate (phytic acid). The precise routes of enzymatic dephosphorylation by phytases of the yeast strains Saccharomyces cerevisiae and Pichia rhodanensis have been investigated up to the myo-inositol trisphosphate level, including the absolute configuration of the intermediates. Stereoselective assignment of the myo-inositol pentakisphosphates (D-myo-inositol 1,2,4,5,6-pentakisphosphate and D-myo-inositol 1,2,3,4,5-pentakisphosphate) generated was accomplished by a new method based on enantiospecific enzymatic conversion and HPLC analysis. Via conduritol B or E derivatives the total syntheses of two epimers of myo-inositol hexakisphosphate, neo-inositol hexakisphosphate and L-chiro-inositol hexakisphosphate were performed to examine the specificity of the yeast phytases with these substrate analogues. A comparison of kinetic data and the degradation pathways determined gave the first hints about the molecular recognition of inositol hexakisphosphates by the enzymes. Exploitation of the high stereo- and regiospecificity observed in the dephosphorylation of neo- and L-chiro-inositol hexakisphosphate made it possible to establish enzyme-assisted steps for the synthesis of D-neo-inositol 1,2,5,6-tetrakisphosphate, L-chiro-inositol 1,2,3,5,6-pentakisphosphate and L-chiro-inositol 1,2,3,6-tetrakisphosphate.
- Adelt, Stephan,Podeschwa, Michael,Dallmann, Guido,Altenbach, Hans-Josef,Vogel, Guenter
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- Stereoselective synthesis of myo-, neo-, L-chiro, D-chiro, allo-, scyllo-, and epi-inositol systems via conduritols prepared from p-benzoquinone
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A practical route is described for the flexible preparation of a wide variety of inositol stereoisomers and their polyphosphates. The potential of this approach is demonstrated by the synthesis of myo-, L-chiro-, D-chiro-, epi-, scyllo-, allo-, and neo-inositol systems. Optically pure compounds in either enantiomeric form can be prepared from p-benzoquinone via enzymatic resolution of a derived conduritol B key intermediate. High-performance anion-exchange chromatography with pulsed amperometric detection permits inositol stereoisomers to be resolved and detected with high sensitivity. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Podeschwa, Michael,Plettenburg, Oliver,Vom Brocke, Jochen,Block, Oliver,Adelt, Stephan,Altenbach, Hans-Josef
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p. 1958 - 1972
(2007/10/03)
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- Efficient synthesis of enantiopure conduritols by ring-closing metathesis
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Two short synthetic approaches to enantiopure conduritols are described starting from the chiral pool. In both cases, the cyclohexene ring is assembled via ring-closing olefin metathesis. The terminal diene precursers for the metathesis reaction are prepared either from octitols or from tartaric acids. The former route involves a new method for selective bromination of the primary positions in long-chain carbohydrate polyols. Subsequent reductive elimination with zinc then generates the diene. The latter route uses a highly diastereoselective addition of divinylzinc to tartaric dialdehydes for preparation of the dienes.
- Jorgensen,Iversen,Paulsen,Madsen
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p. 4630 - 4634
(2007/10/03)
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- An efficient enzymatic preparation of (+)- and (-)-conduritol E, a cyclitol with C2 symmetry
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Lypozyme IM (immobilised lipase from Mucor miehei) catalyses the enantiomeric alcoholysis of tetraacetylconduritol E (±)-2 to give enantiopure (1R,2R,3R,4R)-tetrahydroxycyclohex-5-ene (-)-1, and the unreacted ester (1S,2S,3S,4S)-tetraacetyloxycyclohex-5-ene, (+)-2. The latter was transformed by basic hydrolysis into (+)-1 in high yield and 95% ee. Selective amination of partial ester (-)-3, obtained by short alcoholysis of (±)-2, furnished the previously unreported conduramine F-4, (-)-4.
- Sanfilippo, Claudia,Patti, Angela,Piattelli, Mario,Nicolosi, Giovanni
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p. 1569 - 1573
(2007/10/03)
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- Enzymatic desymmetrisation of conduritol D. Preparation of homochiral intermediates for the synthesis of cyclitols and aminocyclitols
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From meso-conduritol D tetraacetate four homochiral partial derivatives, namely (+)-(1R,2R,3S,4S)-1-hydroxy-2,3,4-triacetoxy-5-cyclohexene, (-)-(1R,2R,3S,4S)-2-hydroxy-1,3,4-triacetoxy-5-cyclohexene, (-)-(1R,2R,3S,4S)-1-benzyloxy-3,4-diacetoxy-2-hydroxy-5-cyclohexene and (+)-(1R,2R,3S,4S)-3,4-diacetoxy-1,2-dihydroxy-5-cyclohexene, have been prepared through enzymatic reactions catalysed by one of the following lipases: from porcine pancreas, from Mucor miehei and from Candida cylindracea. These compounds are of potential utility in the synthesis of cyclitols and aminocyclitols. As an example, the preparation of the previously unreported (+)-conduramine C-4 is also reported.
- Patti, Angela,Sanfilippo, Claudia,Piattelli, Mario,Nicolosi, Giovanni
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p. 2665 - 2670
(2007/10/03)
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