Stability of the enzyme (S)-hydroxynitrile lyase from Hevea brasiliensis

Bauer, Michael; Geyer, Roland; Boy, Matthias; Griengl, Herfried; Steiner, Walter

doi:10.1016/s1381-1177(98)00030-7

Cited by 28 publications

(16 citation statements)

References 9 publications

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“…The activity of the recombinant isoenzyme PaHNL5 did not change significantly over the range pH 2.5-6.5. PaHNL5 was surprisingly stable under acidic conditions (Figure 1), under which the competitive chemical reaction is suppressed [18,19] and the enantiomerically pure cyanohydrin product is also stable. This extremely important technical feature of HNL reactions in emulsion systems makes the production of pure enantiomers possible even from substrates that react slowly and facilitates effective enzyme recycling.…”

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confidence: 99%

Comprehensive Step‐by‐Step Engineering of an (R)‐Hydroxynitrile Lyase for Large‐Scale Asymmetric Synthesis

et al. 2003

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confidence: 99%

Comprehensive Step‐by‐Step Engineering of an (R)‐Hydroxynitrile Lyase for Large‐Scale Asymmetric Synthesis

et al. 2003

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“…[28] The mass transfer limitation is also a powerful tool to enhance the enantiomeric excess. [29,30] In order to understand the underlying limitations within hydroxynitrile lyase-catalyzed ketone cyanohydrin synthesis, we investigated several different reaction systems to overcome the limitations (Figure 1). …”

Section: Resultsmentioning

confidence: 99%

“…The kinetics within the twophase system were intensely studied during the last years. [33,36] On the other hand, the organic solvent-free system affords always a maximum enzyme activity, because the substrate concentration is only limited by the solubility of the substrate in the aqueous phase.…”

Section: Discussionmentioning

confidence: 99%

“…[29,[32][33][34] Unfortunately, only low grades of conversion were obtained for acetophenone cyanohydrin synthesis by using a two-phase system consisting of diisopropyl ether as the organic phase and citrate buffer as the aqueous phase. Even an increase of the substrate concentration leads only to a slight increase of the equilibrium conversion (Table 2).…”

Section: Two-phase Systemmentioning

confidence: 99%

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Hydroxynitrile Lyase in Organic Solvent‐Free Systems to Overcome Thermodynamic Limitations

et al. 2007

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Abstract:The overcoming of thermodynamic limitations in the synthesis of optically active ketone cyanohydrins by using organic solvent-free systems has been investigated. Therefore, substrates with known unfavorable results within hydroxynitrile lyase-catalyzed reactions were selected for the determination of limitations and bottlenecks in ketone cyanohydrin synthesis. The highly (S)-selective hydroxynitrile lyase from Manihot esculenta (MeHNL) has been chosen for the conversion of acetophenone and the corresponding derivatives, which are substrates that exhibit only low grades of conversion also with several other hydroxynitrile lyases. With organic solventfree systems under optimized reaction conditions conversions up to 78 % with > 99.0 ee (S) were obtained. Finally, 5 mL of (S)-acetophenone cyanohydrin with an enantiomeric excess of 98.5 % ee (S) were synthesized.

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“…The mass transfer limitation is also a powerful tool to enhance the enantiomeric excess [21,22]. Disadvantageously, these procedures reduce also the enzyme activity and result in higher enzyme costs.…”

Section: Introductionmentioning

confidence: 99%

Hydroxynitrile lyase catalyzed cyanohydrin synthesis at high pH-values

Langermann

Guterl

Pohl

et al. 2008

Bioprocess Biosyst Eng

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The application of unusual high pH-values within enzymatic cyanohydrin synthesis has been investigated. Usually enzymatic cyanohydrin synthesis in two-phase systems requires low pH-values within the aqueous phase to suppress the non-enzymatic side reaction. In contrast, we investigated the usage of pH-values above pH 6 by using the highly enantioselective (S)-selective hydroxynitrile lyase from Manihot esculenta. With these unusual reaction conditions also the unfavorable substrate 3-phenoxy-benzaldehyde can be converted by the wild type enzyme with excellent conversion and enantiomeric excess yielding pure (S)-3-phenoxy-benzaldehyde cyanohydrin with an enantiomeric excess of 97%. Although the variant MeHNL-W128A shows a higher activity with respect to this reaction, the enantioselectivity was reduced (85% e.e.(S)). Additionally, a new continuous spectroscopic cyanohydrin assay monitoring the formation of 3-phenoxy-benzaldehyde cyanohydrin was developed.

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Stability of the enzyme (S)-hydroxynitrile lyase from Hevea brasiliensis

Cited by 28 publications

References 9 publications

Comprehensive Step‐by‐Step Engineering of an (R)‐Hydroxynitrile Lyase for Large‐Scale Asymmetric Synthesis

Comprehensive Step‐by‐Step Engineering of an (R)‐Hydroxynitrile Lyase for Large‐Scale Asymmetric Synthesis

Hydroxynitrile Lyase in Organic Solvent‐Free Systems to Overcome Thermodynamic Limitations

Hydroxynitrile lyase catalyzed cyanohydrin synthesis at high pH-values

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