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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.


Activity of enzymes with increasing concentration of surfactant. (A) CZ activity declines steeply around 2 mM SDS while RL has little effect on activity. (B) LT activity is increased between 0 and 1 mM SDS where after it declines to ~0% between 1 and 2 mM SDS. LT activity is decreased at low RL concentration but increases at concentrations above the cmc. (C) SZ activity is only slightly affected by both SDS and RL.
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Figure 6: Activity of enzymes with increasing concentration of surfactant. (A) CZ activity declines steeply around 2 mM SDS while RL has little effect on activity. (B) LT activity is increased between 0 and 1 mM SDS where after it declines to ~0% between 1 and 2 mM SDS. LT activity is decreased at low RL concentration but increases at concentrations above the cmc. (C) SZ activity is only slightly affected by both SDS and RL.

Mentions: To further consolidate our understanding of the difference in how the two anionic surfactants interact with enzymes, we monitored the enzymatic stabilities of all three enzymes as a function of surfactant concentration. Our results (Figures 6A–C) nicely corroborate the stability data. The activity of CZ in SDS increases slightly at low SDS concentrations, but then starts to decline steeply around 2 mM SDS (Figure 6A), exactly the same concentration range where our CD data indicate onset of unfolding. Activity is retained in RL at all concentrations, consistent with our CD data.


The anionic biosurfactant rhamnolipid does not denature industrial enzymes.

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

Activity of enzymes with increasing concentration of surfactant. (A) CZ activity declines steeply around 2 mM SDS while RL has little effect on activity. (B) LT activity is increased between 0 and 1 mM SDS where after it declines to ~0% between 1 and 2 mM SDS. LT activity is decreased at low RL concentration but increases at concentrations above the cmc. (C) SZ activity is only slightly affected by both SDS and RL.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Activity of enzymes with increasing concentration of surfactant. (A) CZ activity declines steeply around 2 mM SDS while RL has little effect on activity. (B) LT activity is increased between 0 and 1 mM SDS where after it declines to ~0% between 1 and 2 mM SDS. LT activity is decreased at low RL concentration but increases at concentrations above the cmc. (C) SZ activity is only slightly affected by both SDS and RL.
Mentions: To further consolidate our understanding of the difference in how the two anionic surfactants interact with enzymes, we monitored the enzymatic stabilities of all three enzymes as a function of surfactant concentration. Our results (Figures 6A–C) nicely corroborate the stability data. The activity of CZ in SDS increases slightly at low SDS concentrations, but then starts to decline steeply around 2 mM SDS (Figure 6A), exactly the same concentration range where our CD data indicate onset of unfolding. Activity is retained in RL at all concentrations, consistent with our CD data.

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.