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Sodium dodecyl sulfate monomers induce XAO peptide polyproline II to ?-helix transition.

ABSTRACT: XAO peptide (Ac-X2A7O2-NH2; X: diaminobutyric acid side chain, -CH2CH2NH3(+); O: ornithine side chain, -CH2CH2CH2NH3(+)) in aqueous solution shows a predominantly polyproline II (PPII) conformation without any detectable ?-helix-like conformations. Here we demonstrate by using circular dichroism (CD), ultraviolet resonance Raman (UVRR) and nuclear magnetic resonance (NMR) spectroscopy that sodium dodecyl sulfate (SDS) monomers bind to XAO and induce formation of ?-helix-like conformations. The stoichiometry and the association constants of SDS and XAO were determined from the XAO-SDS diffusion coefficients measured by pulsed field gradient NMR. We developed a model for the formation of XAO-SDS aggregate ?-helix-like conformations. Using UVRR spectroscopy, we calculated the Ramachandran ? angle distributions of aggregated XAO peptides. We resolved ?-, ?- and 3(10)-helical conformations and a turn conformation. XAO nucleates SDS aggregation at SDS concentrations below the SDS critical micelle concentration. The XAO4-SDS16 aggregates have four SDS molecules bound to each XAO to neutralize the four side chain cationic charges. We propose that the SDS alkyl chains partition into a hydrophobic core to minimize the hydrophobic area exposed to water. Neutralization of the flanking XAO charges enables ?-helix formation. Four XAO-SDS4 aggregates form a complex with an SDS alkyl chain-dominated hydrophobic core and a more hydrophilic shell where one face of the ?-helix peptide contacts the water environment.

SUBMITTER: Hong Z

PROVIDER: S-EPMC4161145 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

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Sodium dodecyl sulfate monomers induce XAO peptide polyproline II to α-helix transition.

Hong Zhenmin Z Damodaran Krishnan K Asher Sanford A SA

The journal of physical chemistry. B 20140902 36

XAO peptide (Ac-X2A7O2-NH2; X: diaminobutyric acid side chain, -CH2CH2NH3(+); O: ornithine side chain, -CH2CH2CH2NH3(+)) in aqueous solution shows a predominantly polyproline II (PPII) conformation without any detectable α-helix-like conformations. Here we demonstrate by using circular dichroism (CD), ultraviolet resonance Raman (UVRR) and nuclear magnetic resonance (NMR) spectroscopy that sodium dodecyl sulfate (SDS) monomers bind to XAO and induce formation of α-helix-like conformations. The s ...[more]

PMID: 25121643

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Project description:The number and type of synthetic chemicals that are being produced worldwide continues to increase significantly. While these industrial chemicals provide numerous benefits, there is no doubt that some have potential to damage the environment and health. Toxicity must be evaluated and use must be carefully controlled and monitored in order to minimize potential damage. DNA microarray technology has become an important new technique in toxicology. We are using the yeast Saccharomyces cerevisiae as a model organism for toxicological study because it is a simple, fast-growing eukaryote that has been thoroughly characterized. In order to evaluate toxicity by newly synthesized or mixture chemicals, toxicity-induced gene expression alteration profiles by known chemicals should be collected. In our study, cells need to be exposed with same experimental cellular condition, semi lethal (IC50), respectively. In the case of SDS (CAS; 151-21-3), the exposure dose was decided as 0.01% by growth curve with continuously diluted exposure. SDS is an anionic surfactant that is suspected to be gastrointestinal or liver toxicant. // Toxicity of anionic detergents determined by Saccharomyces cerevisiae microarray analysis: Sodium n-dodecyl benzene sulfonate (LAS) and sodium dodecyl sulfate (SDS) are popular anionic detergents (surfactants) that are used worldwide and the toxicities of these chemicals have been characterized. We applied these chemicals in a DNA microarray bioassay and determined that the microarray data reflects previous findings and also provides some new information about anionic detergent toxicity. The mRNA expression profiles suggest that LAS and SDS cause damage to membranes and alterations in carbon metabolism, and induce the oxidative stress response. We also found that LAS and SDS induce the pleiotropic drug-resistance network, and that LAS and SDS may be pumped out of yeast cells by this network. Hierarchical clustering of the expression profiles showed that LAS and SDS cause similar features of toxicity and that the toxicity is similar to that of capsaicin but different from that of cadmium and mercury. Keywords: stress response

Dataset Information

Sodium dodecyl sulfate monomers induce XAO peptide polyproline II to ?-helix transition.

Publications

Sodium dodecyl sulfate monomers induce XAO peptide polyproline II to α-helix transition.

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