Sodium N-lauroylsarcosinate is a naturally-occurring ingredient that is derived from the amino acid sarcosine. It is used as a foaming and cleansing ingredient in shampoos, body washes, shaving foams and toothpastes. Sodium N-lauroylsarcosinate is a surfactant which means that due to it being both hydrophilic, water-loving and hydrophobic, water-hating, it is able to lift oils and dirt from the skin. It can often be confused with Sodium dodecyl sulfate due to the similarity in function and the similarity in the name. However, the two ingredients are different in that Sodium dodecyl sulfate is considered to be a gentler, milder cleansing ingredient.

Synthesis

Equipped with a thermometer, a dropping funnel, a stirring 1000mL four-necked flask, sarcosine was added 111g (1mol), was dissolved in 333g water and stirred at ambient temperature after it has completely dissolved, dubbed 25% aqueous solution of lauryl chloride 240g (1.1mol) into a dry dropping funnel, temperature control of 15~20 ° C in an ice-water bath, was added lauroyl chloride with stirring while a solution of 25% aqueous sodium hydroxide solution, the reaction solution has been in ρΗ = 8~10, until the completion of the addition; the reaction was continued 4~5 h. After the reaction, 6N hydrochloric acid with pH adjusted to ~ 2, there are a large number of white crystals precipitated, the precipitation until all the product was filtered and dried to give 260g lauroyl sarcosine, 96% yield. The lauroyl sarcosine 271g (1mol) was dissolved in 608g of ethanol was added 20% aqueous sodium hydroxide (1mol) in ethanol 200g, cooled -5~5 ° C, the precipitated crystals were suction filtered, after drying, to obtain Sodium N-lauroylsarcosinate 284g, yield 97% square.[1]

Applications

A Good Regeneration Neagent

A new regeneration condition has been established for binding interaction studies of soluble proteins by using V-ATPase subunits as examples. Sodium N-lauroylsarcosinate also seemed to work well for other kinds of interactions such as was shown for anti-Penta-His antibody–His6NtpB interaction. Sodium N-lauroylsarcosinate at low concentrations was able to dissociate the ligand–analyte binding, leaving the ligand active. Sodium N-lauroylsarcosinate is a mild detergent, whereas SDS is harsh, having the probability to denature ligand and, thus, affect the next cycle. Furthermore, in the case of Sodium N-lauroylsarcosinate, comprehensive consistency was observed and the reproducibility was found to be complete in various combinations of protein–protein binding interactions, and we did not observe any ligand deterioration in any case. Finally, the use of Sodium N-lauroylsarcosinate was found to be safe, reliable, and satisfactory for sensitive protein–protein binding interaction research and can be used as an excellent regeneration reagent for Biacore experimenters.[2]

A mild Detergent

Sodium dodecyl sulfate (SDS) is a detergent used as a strong denaturant of proteins in gel electrophoresis. It has previously been shown that certain hyperstable, also known as kinetically stable, proteins are resistant to SDS and thus require heating for their denaturation in the presence of SDS. Because of its high denaturing strength, relatively few proteins are resistant to SDS thereby limiting the current use of SDS-PAGE for identifying hyperstable degradation-resistant proteins. In this study, we show that Sodium N-lauroylsarcosinate, a milder detergent than SDS, is able to identify proteins with moderately high kinetic stability that lack SDS-resistance. Our assay involves running and subsequently comparing boiled and unheated protein samples containing Sodium N-lauroylsarcosinate, instead of SDS, on PAGE gels and identifying subsequent differences in protein migration. Our results also show that Sodium N-lauroylsarcosinate and SDS may be combined in PAGE experiments at varying relative percentages to obtain semi-quantitative information about a protein's kinetic stability in a range inaccessible by probing through native- or SDS-PAGE. Using protein extracts from various legumes as model systems, we detected proteins with a range of protein stability from nearly SDS-resistant to barely Sodium N-lauroylsarcosinate resistant.

In search of a denaturing detergent milder than SDS, the initial approach was to test commercially available detergents similar to SDS in terms of size, being anionic, and possessing a comparable hydrophobic chain. Of the various detergents tested, sodium decyl sulfate and sodium lauroyl sarcosinate (Sodium N-lauroylsarcosinate) were found to be most promising. We decided to focus on Sodium N-lauroylsarcosinate due to its 10-fold lower cost. Sodium N-lauroylsarcosinate has been known for decades to be a milder detergent than SDS, although many proteins may be denatured by Sodium N-lauroylsarcosinate at room temperature (see several examples in . Sodium N-lauroylsarcosinate has been used extensively to solubilize a variety of aggregation-prone proteins, including those from membrane, cytoskeleton, and inclusion bodies. Sodium N-lauroylsarcosinate is also commonly used in soap and other cosmetic products due to its foaming and cleansing ability. The structure of Sodium N-lauroylsarcosinate is similar to that of SDS in the hydrophobic tail, but differs significantly in the polar head. Instead of a sulfate group, Sodium N-lauroylsarcosinate has a less polar carboxylate head next to a methyl amide moiety.[3]

The denaturing capacity of Sodium N-lauroylsarcosinate in relation to SDS was tested by running boiled and unheated samples of legume extracts under different relative percentage of Sodium N-lauroylsarcosinate and SDS in the sample buffer and running buffer. For comparison, the same samples were also analyzed by SDS-PAGE. Six legumes were chosen that were previously shown to contain storage proteins with minimal SDS-resistance, including lentil, split green pea, chickpea, pigeon pea, kidney bean, and mung bean. For each legume extract, samples were either left unheated or boiled in a 1% (w/v) detergent solution and run as a corresponding SAR- or SDS- PAGE gel. Most of the proteins migrated through the SDS-PAGE gels the same distance regardless of heating. A notable exception was kidney bean, whose known storage KSP, phaseolin, shows a moderate degree of smearing, suggesting marginal SDS-resistance. Indeed, it was the observation of partial SDS-resistance by kidney bean phaseolin that led to this study in search for a denaturing detergent milder than SDS. The observation of legume proteins resistant to Sodium N-lauroylsarcosinate but not SDS led us to inquire whether mixing Sodium N-lauroylsarcosinate and SDS in PAGE may provide a quantitative assessment of protein kinetic stability. Therefore, SAR-SDS-PAGE experiments were carried out in which the total detergent concentration was kept at 1% (w/v), but the relative concentration of SDS was varied from 0 to 100%. Separate PAGE experiments were required for each Sodium N-lauroylsarcosinate and SDS concentration in order to match the desired detergent composition in the running buffer and sample buffer.

References

[1] CHANGSHA PUJI BIOLOG TECHNOLOGY - CN102875409, 2016, B

[2] B. Lang, M. Delmar, W. Coombs (Eds.), Practical Methods in Cardiovascular Research, Part 3, Springer, New York (2005), pp. 936-947

[3] Proc. Natl. Acad. Sci. U.S.A., 66 (1970), pp. 1002-1007