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The anionic biosurfactant rhamnolipid does not denature industrial enzymes.

Madsen JK, Pihl R, Møller AH, Madsen AT, Otzen DE, Andersen KK - Front Microbiol (2015)

Bottom Line: It efficiently unfolds both LT and CZ, but LT is unfolded by SDS through formation of SDS clusters on the enzyme well below the cmc, while CZ is only unfolded by bulk micelles and on average binds significantly less SDS than LT.In contrast, RL does not affect the tertiary or secondary structure of any enzyme at room temperature, has little impact on thermal stability and only binds detectably (but at low stoichiometries) to SZ.Furthermore, all enzymes maintain activity at both monomeric and micellar concentrations of RL.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology and Genetics, Aarhus University Aarhus, Denmark.

ABSTRACT
Biosurfactants (BS) are surface-active molecules produced by microorganisms. Their combination of useful properties and sustainable production make them promising industrial alternatives to petrochemical and oleochemical surfactants. Here we compare the impact of the anionic BS rhamnolipid (RL) and the conventional/synthetic anionic surfactant sodium dodecyl sulfate (SDS) on the structure and stability of three different commercially used enzymes, namely the cellulase Carezyme® (CZ), the phospholipase Lecitase Ultra® (LT) and the α-amylase Stainzyme® (SZ). Our data reveal a fundamental difference in their mode of interaction. SDS shows great diversity of interaction toward the different enzymes. It efficiently unfolds both LT and CZ, but LT is unfolded by SDS through formation of SDS clusters on the enzyme well below the cmc, while CZ is only unfolded by bulk micelles and on average binds significantly less SDS than LT. SDS binds with even lower stoichiometry to SZ and leads to an increase in thermal stability. In contrast, RL does not affect the tertiary or secondary structure of any enzyme at room temperature, has little impact on thermal stability and only binds detectably (but at low stoichiometries) to SZ. Furthermore, all enzymes maintain activity at both monomeric and micellar concentrations of RL. We conclude that RL, despite its anionic charge, is a surfactant that does not compromise the structural integrity of industrially relevant enzymes. This makes RL a promising alternative to current synthetic anionic surfactants in a wide range of commercial applications.

No MeSH data available.


Using ITC to determine the binding stoichiometry of surfactants to LT. (A) Enthalpograms for the titration of SDS into LT. (B) Representative enthalpograms which illustrate inflection points used to calculate binding numbers. (C) SDS inflection points plotted as a function of LT concentration. The linear fit to Equation (1) provides binding numbers (see text). (D) Titration of RL into LT did not show any significant effect of the presence of the enzyme.
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Figure 7: Using ITC to determine the binding stoichiometry of surfactants to LT. (A) Enthalpograms for the titration of SDS into LT. (B) Representative enthalpograms which illustrate inflection points used to calculate binding numbers. (C) SDS inflection points plotted as a function of LT concentration. The linear fit to Equation (1) provides binding numbers (see text). (D) Titration of RL into LT did not show any significant effect of the presence of the enzyme.

Mentions: Dilution of micellar SDS into buffer resulted in an endothermic signal at low SDS concentrations as a result of the dissociation of SDS micelles (Figure 7A). Above 2 mM SDS there is a decrease in the endothermic signal which levels out from around 3 mM SDS, indicating that no demicellization occurs. Thus, ITC concurs with pyrene fluorescence in establishing SDS's cmc to be around 2–3 mM in our buffer system.


The anionic biosurfactant rhamnolipid does not denature industrial enzymes.

Madsen JK, Pihl R, Møller AH, Madsen AT, Otzen DE, Andersen KK - Front Microbiol (2015)

Using ITC to determine the binding stoichiometry of surfactants to LT. (A) Enthalpograms for the titration of SDS into LT. (B) Representative enthalpograms which illustrate inflection points used to calculate binding numbers. (C) SDS inflection points plotted as a function of LT concentration. The linear fit to Equation (1) provides binding numbers (see text). (D) Titration of RL into LT did not show any significant effect of the presence of the enzyme.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4400916&req=5

Figure 7: Using ITC to determine the binding stoichiometry of surfactants to LT. (A) Enthalpograms for the titration of SDS into LT. (B) Representative enthalpograms which illustrate inflection points used to calculate binding numbers. (C) SDS inflection points plotted as a function of LT concentration. The linear fit to Equation (1) provides binding numbers (see text). (D) Titration of RL into LT did not show any significant effect of the presence of the enzyme.
Mentions: Dilution of micellar SDS into buffer resulted in an endothermic signal at low SDS concentrations as a result of the dissociation of SDS micelles (Figure 7A). Above 2 mM SDS there is a decrease in the endothermic signal which levels out from around 3 mM SDS, indicating that no demicellization occurs. Thus, ITC concurs with pyrene fluorescence in establishing SDS's cmc to be around 2–3 mM in our buffer system.

Bottom Line: It efficiently unfolds both LT and CZ, but LT is unfolded by SDS through formation of SDS clusters on the enzyme well below the cmc, while CZ is only unfolded by bulk micelles and on average binds significantly less SDS than LT.In contrast, RL does not affect the tertiary or secondary structure of any enzyme at room temperature, has little impact on thermal stability and only binds detectably (but at low stoichiometries) to SZ.Furthermore, all enzymes maintain activity at both monomeric and micellar concentrations of RL.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology and Genetics, Aarhus University Aarhus, Denmark.

ABSTRACT
Biosurfactants (BS) are surface-active molecules produced by microorganisms. Their combination of useful properties and sustainable production make them promising industrial alternatives to petrochemical and oleochemical surfactants. Here we compare the impact of the anionic BS rhamnolipid (RL) and the conventional/synthetic anionic surfactant sodium dodecyl sulfate (SDS) on the structure and stability of three different commercially used enzymes, namely the cellulase Carezyme® (CZ), the phospholipase Lecitase Ultra® (LT) and the α-amylase Stainzyme® (SZ). Our data reveal a fundamental difference in their mode of interaction. SDS shows great diversity of interaction toward the different enzymes. It efficiently unfolds both LT and CZ, but LT is unfolded by SDS through formation of SDS clusters on the enzyme well below the cmc, while CZ is only unfolded by bulk micelles and on average binds significantly less SDS than LT. SDS binds with even lower stoichiometry to SZ and leads to an increase in thermal stability. In contrast, RL does not affect the tertiary or secondary structure of any enzyme at room temperature, has little impact on thermal stability and only binds detectably (but at low stoichiometries) to SZ. Furthermore, all enzymes maintain activity at both monomeric and micellar concentrations of RL. We conclude that RL, despite its anionic charge, is a surfactant that does not compromise the structural integrity of industrially relevant enzymes. This makes RL a promising alternative to current synthetic anionic surfactants in a wide range of commercial applications.

No MeSH data available.