On the validity of the optimum micelle size approach in the study of micellar solutions

Rao, I.V; Ruckenstein, Eli

doi:10.1016/0021-9797(87)90261-x

Cited by 28 publications

(8 citation statements)

References 24 publications

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“…It was experienced at each temperature that, while mic H was only slightly influenced by this storage, the cmc was shifted to a concentration significantly lower than that obtained when using the freshly made, stock solution. Since the cmc-decreasing effect of alcohols has been well established experimentally (15,16), it seemed reasonable to assume that the lowering of the cmc of SDeS upon storage can be attributed to the appearance of n-decanol, a product of the self-hydrolysis of SDeS. To check this hypothesis, we added n-decanol (10 mM) to a freshly made SDeS stock solution (300 mM) and measured the enthalpies of dilution of this micellar solution into water.…”

Section: Resultsmentioning

confidence: 99%

A Thermometric Titration Study on the Micelle Formation of Sodium Decyl Sulfate in Water

Király

Dékány

2001

Journal of Colloid and Interface Science

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Section: Resultsmentioning

confidence: 99%

A Thermometric Titration Study on the Micelle Formation of Sodium Decyl Sulfate in Water

Király

Dékány

2001

Journal of Colloid and Interface Science

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“…We initially applied DEER to WT ␣S spin labeled at positions 24/61 at a protein concentration of 100 M and detergent concentrations well above the expected critical micelle concentration of around 1 mM (25, 42) that, based on previous studies (25,43,44), are associated with the presence of either spheroidal (40 mM SDS) or cylindrical (450 mM SDS) micelles. We obtained distances corresponding to the broken and extended helix states (not shown), respectively, as expected based on previous ESR studies of ␣S at these SDS concentrations (20,21).…”

Section: Inter-spin Distances In Membrane-bound ␣Smentioning

confidence: 99%

The Lipid-binding Domain of Wild Type and Mutant α-Synuclein

Georgieva

Ramlall

Borbat

et al. 2010

Journal of Biological Chemistry

134

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␣-Synuclein (␣S) is linked to Parkinson disease through its deposition in an amyloid fibril form within Lewy Body deposits, and by the existence of three ␣S point mutations that lead to early onset autosomal dominant Parkinsonism. The normal function of ␣S is thought to be linked to the ability of the protein to bind to the surface of synaptic vesicles. Upon binding to vesicles, ␣S undergoes a structural reorganization from a dynamic and disordered ensemble to a conformation consisting of a long extended helix. In the presence of small spheroidal detergent micelles, however, this extended helix conformation can convert into a broken helix state, in which a region near the middle of the helix unwinds to form a linker between the two resulting separated helices. Membrane-bound conformations of ␣S likely mediate the function of the protein, but may also play a role in the aggregation and toxicity of the protein. Here we have undertaken a study of the effects of the three known PD-linked mutations on the detergent-and membrane-bound conformations of ␣S, as well as factors that govern the transition of the protein between the extended helix and broken helix states. Using pulsed dipolar ESR measurements of distances up to 8.7 nm, we show that all three PD-linked ␣S mutants retain the ability to transition from the broken helix to the extended helix conformation. In addition, we find that the ratio of protein to detergent, rather than just the absolute detergent concentration, determines whether the protein adopts the broken or extended helix conformation.Since its initial discovery as a protein enriched in the electric organ of the Pacific electric ray, Torpedo californica (1), the protein ␣-synuclein has been progressively associated with a role in neurodegeneration in humans, starting with its identification as the precursor protein of a non-amyloid-␤ peptide component of amyloid plaques (the so-called NAC peptide) (2) and culminating in its discovery as the first gene product to be linked to familial Parkinson disease (3) and its contemporaneous identification as the primary component of the fibrillary aggregates found in the hallmark Lewy body deposits associated with Parkinson (4).Subsequently, a great deal of effort has been made to clarify and understand the mechanisms by which ␣S causes neuronal degeneration, as well as to understand the normal functional roles of ␣S and how these are related to its role in disease (5, 6). Although aggregation of ␣S remains a key focus in these efforts, it remains possible that other, or additional, effects beyond the presence of various aggregated species of ␣S may be involved in the etiology of synuclein-associated PD. A key piece of the puzzle that remains unanswered is which of the various forms of ␣S that have been observed in vitro are involved in mediating the toxicity of the protein in vivo. In particular, although ␣S is highly disordered when isolated in solution in vitro (7-9) it is not clear to what extent this intrinsically disordered state is populated in vivo. Be...

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“…The difficulties in the theory arise especially from the treatment of electrostatic interactions. One instructive theoretical paper by Rao and Ruckenstein 43 deals with this problem. The authors used in the framework of molecular thermodynamic models [44][45][46][47] two approaches, the optimal micelle size approach and the size distribution model for a theoretical description.…”

Section: Iii232 Dependence On Ionicmentioning

confidence: 99%

Micellar Properties of Sodium Sulfopropyl Alkyl Maleates in Aqueous SolutionA Time-Resolved Fluorescence Quenching Study

1996

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The aggregation behavior of four sodium sulfopropyl alkyl maleates with alkyl chain carbon numbers 12, 14, 16, and 18 has been investigated in aqueous solution as a function of surfactant concentration, added sodium chloride concentration, and temperature by means of electrical conductivity and timeresolved fluorescence quenching (TRFQ). Critical micelle concentration and micelle ionization degree decrease upon increasing chain length, exhibiting the classical behavior for straight alkyl chain surfactants, whereas the Krafft temperature, T K, increases. The aggregation numbers have been found to decrease with increasing temperature between TK and 65 °C, with the magnitude of decrease becoming higher for longer hydrophobic chains. The surfactants show micellar growth with surfactant and salt concentration. Whereas the increase of the aggregation number N with ionic strength I is generally weak and follows in good approximation the power law relation N ∝ I β , with a unique exponent β = 0.13 below a surfactantdependent characteristic threshold ionic strength, I*, N steeply increases beyond I*. The values of N indicate that the micelles are probably spheroidal below I*. The micellar polydispersity is generally low for ionic strength I < I* and increases with I, in agreement with the theory of micellization.

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On the validity of the optimum micelle size approach in the study of micellar solutions

Cited by 28 publications

References 24 publications

A Thermometric Titration Study on the Micelle Formation of Sodium Decyl Sulfate in Water

A Thermometric Titration Study on the Micelle Formation of Sodium Decyl Sulfate in Water

The Lipid-binding Domain of Wild Type and Mutant α-Synuclein

Micellar Properties of Sodium Sulfopropyl Alkyl Maleates in Aqueous SolutionA Time-Resolved Fluorescence Quenching Study

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