Role of organic solvents on Pa‐hydroxynitrile lyase interfacial activity and stability

Hickel, Andrea; Radke, Clayton J.; Blanch, Harvey W.

doi:10.1002/bit.1091

Cited by 29 publications

(47 citation statements)

References 17 publications

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“…After enzyme had been washed out of the aqueous phase in a biphasic reactor, Hickel et al (2001) showed that 0-30% of the original reaction rate was found back in the reactor. This does not prove, however, that originally more than 30% of the reaction occurred at the interface.…”

Section: Each Curve Inmentioning

confidence: 99%

“…The preceding discussion shows that the PaHNLcatalyzed reaction in a biphasic liquid has been interpreted as mass-transfer limited (Willeman et al, 2002a) but also in terms of interfacial enzyme adsorption (Hickel et al, 1999(Hickel et al, , 2001. Quantitative comparison of the conditions of these authors is difficult so far.…”

Section: Introductionmentioning

confidence: 96%

“…In some cases it has been used for proteins adsorbing on interfaces, such as casein (Min et al, 1998), but this was not related to any catalytic activity of the protein. However, Hickel et al (1999Hickel et al ( , 2001 and Cascão-Pereira et al (2002a,b) have used the term "interfacial activity" for Prunus amygdalus hydroxynitrile lyase (PaHNL) to indicate not only that it adsorbs on the interface but also to indicate that it is the adsorbed PaHNL rather than the PaHNL in bulk solution that performs the observed catalysis. Their observations did not point at the occurrence of "interfacial activation" as for lipases.…”

Section: Introductionmentioning

confidence: 97%

“…Quantitative comparison of the conditions of these authors is difficult so far. Hickel et al (1999Hickel et al ( , 2001 do not indicate a reaction temperature or a mass transfer coefficient, and Willeman et al (2002a) indicate no interfacial area.…”

Section: Introductionmentioning

confidence: 99%

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Enzymatic catalysis via liquid–liquid interfaces

Straathof

2003

Biotech & Bioengineering

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Enzymes acting in a biphasic liquid of water and organic solvent may show catalytic activity dependent on the amount of phase interface available. Such an effect may be caused by several mechanisms. For example, for hydroxynitrile lyase from Prunus amygdalus, substrate mass transfer limitation has been advocated, but also adsorption of the enzyme on the interface. In this commentary it is shown that often these two mechanisms will have qualitatively similar consequences. The reaction rate will be influenced by the organic substrate concentration, by the initial enzyme concentration, and by the volume-specific interfacial area, and these influences will be linear at low values but reach a saturation level at high values. To rule out any of the models, their quantitative mathematical descriptions should be compared, taking into account that both models may be valid simultaneously.

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Section: Each Curve Inmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Enzymatic catalysis via liquid–liquid interfaces

Straathof

2003

Biotech & Bioengineering

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“…In addition to reiterating the original supporting data for this conclusion (Hickel et al, 1999), we provide further experimental evidence from a recent study on the role of solvents in biphasic pa-Hnl catalysis (Hickel et al, 2001). We also adopt the aqueous-phase homogeneousreaction picture of Willeman et al (2002) and demonstrate that such a model does not reproduce our experimental findings.…”

Section: Introductionmentioning

confidence: 56%

Interfacial versus homogeneous enzymatic cleavage of mandelonitrile by hydroxynitrile lyase in a biphasic system

Cascão-Pereira¹,

Hickel²,

Radke³

et al. 2003

Biotech & Bioengineering

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The question of an interfacial versus a homogeneous reaction is carefully addressed for the enzymatic biphasic cleavage of mandelonitrile to benzaldehyde by Prunus amygdalus hydroxynitrile lyase (pa-Hnl) (Hickel et al. [1999] Biotechnol Bioeng 36:425-436). Experimental evidence, including 1) the reaction ceases when the interface is populated by previously adsorbed denatured pa-Hnl, 2) the reaction continues even after washout of the bulk enzyme from the aqueous phase, 3) highly nonpolar organic solvents initially promote fast reaction kinetics that relatively quickly decay to zero product production, and 4) the reaction rate is nonlinear in the bulk enzyme concentration, provide robust grounds for an interfacial reaction. We also model enzymatic mandelonitrile cleavage assuming a homogeneous aqueous-phase reaction. The homogeneous reaction scheme does not simultaneously account for the experimental observations of a linear dependence of the reaction rate on organic/water interfacial area, no dependence on the aqueous-phase volume, and a nonlinear dependence on pa-Hnl aqueous concentration. Further, simple calculations demonstrate that the homogeneous reaction rate is at least three orders of magnitude slower than those observed by Hickel et al. (1999). We again conclude that enzyme adsorbed at the organic solvent/water interface primarily catalyzes the biphasic mandelonitrile cleavage reaction.

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Catalyst Deactivation/Regeneration – Biological

Drevon

Russell

2002

Encyclopedia of Catalysis

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Biocatalyst inactivation is caused by external stresses, including high pressures and temperatures, extreme pH's, organic media, freezing, drying, and oxidative, chelating, and denaturing agents. These stresses may result either in reversible or irreversible activity loss. The main structural and covalent mechanisms in biocatalyst inactivation such as the disulfide intra‐ and interexchanges, the deamidation of asparagine residues, the decomposition of disulfide bridges by β‐elimination, the hydrolysis of peptide chains, the β‐isomerization of asparagine and aspartic acid residues, and amino acid racemization are discussed. The strategies that have been developed to prevent biocatalyst inactivation, i.e. chemical modification immobilization, protein engineering, directed evolution, are briefly presented.

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Role of organic solvents on Pa‐hydroxynitrile lyase interfacial activity and stability

Cited by 29 publications

References 17 publications

Enzymatic catalysis via liquid–liquid interfaces

Enzymatic catalysis via liquid–liquid interfaces

Interfacial versus homogeneous enzymatic cleavage of mandelonitrile by hydroxynitrile lyase in a biphasic system

Catalyst Deactivation/Regeneration – Biological

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