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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.


Change in (A,B) secondary and (C,D) tertiary structure of LT with increasing surfactant concentration. (A) Far-UV and (C) near-UV CD spectra of LT in buffer and in the presence of surfactants. Spectra of LT in buffer and with RL are essentially identical, while SDS induces changes in both secondary and tertiary structure. (B) Changes in the ellipticity ratio 220/207 nm reveal a structural change at 1 mM, i.e., below the cmc. (D) Changes in the ellipticity at 283.5 nm confirm that a structural change is induced by SDS below its cmc.
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Figure 3: Change in (A,B) secondary and (C,D) tertiary structure of LT with increasing surfactant concentration. (A) Far-UV and (C) near-UV CD spectra of LT in buffer and in the presence of surfactants. Spectra of LT in buffer and with RL are essentially identical, while SDS induces changes in both secondary and tertiary structure. (B) Changes in the ellipticity ratio 220/207 nm reveal a structural change at 1 mM, i.e., below the cmc. (D) Changes in the ellipticity at 283.5 nm confirm that a structural change is induced by SDS below its cmc.

Mentions: In the case of LT, the enzyme preserves native tertiary and secondary structure in the presence of RL monomers and micelles, while SDS leads to large changes in both secondary and tertiary structure (Figures 3A,C). The change in both secondary and tertiary structure is induced already around 1 mM SDS and the transition is complete around 2 mM SDS (Figures 3B,D). This indicates that LT is denatured below the cmc and therefore by SDS monomers.


The anionic biosurfactant rhamnolipid does not denature industrial enzymes.

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

Change in (A,B) secondary and (C,D) tertiary structure of LT with increasing surfactant concentration. (A) Far-UV and (C) near-UV CD spectra of LT in buffer and in the presence of surfactants. Spectra of LT in buffer and with RL are essentially identical, while SDS induces changes in both secondary and tertiary structure. (B) Changes in the ellipticity ratio 220/207 nm reveal a structural change at 1 mM, i.e., below the cmc. (D) Changes in the ellipticity at 283.5 nm confirm that a structural change is induced by SDS below its cmc.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Change in (A,B) secondary and (C,D) tertiary structure of LT with increasing surfactant concentration. (A) Far-UV and (C) near-UV CD spectra of LT in buffer and in the presence of surfactants. Spectra of LT in buffer and with RL are essentially identical, while SDS induces changes in both secondary and tertiary structure. (B) Changes in the ellipticity ratio 220/207 nm reveal a structural change at 1 mM, i.e., below the cmc. (D) Changes in the ellipticity at 283.5 nm confirm that a structural change is induced by SDS below its cmc.
Mentions: In the case of LT, the enzyme preserves native tertiary and secondary structure in the presence of RL monomers and micelles, while SDS leads to large changes in both secondary and tertiary structure (Figures 3A,C). The change in both secondary and tertiary structure is induced already around 1 mM SDS and the transition is complete around 2 mM SDS (Figures 3B,D). This indicates that LT is denatured below the cmc and therefore by SDS monomers.

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.