Surfactant from forest soil

Fig. 4.3. High performance liquid chromatography (HPLC) of the monosaccharides obtained from a partially purified preparation of microbubble glycopeptide surfactant from forest soil. Following hydrolysis (in 2 N HC1 for 6 hr at 100°C) and filtration, the carbohydrate mixture was charged on a Bio-Rad HPX-87 cation exchange column. For comparison, part A shows the chromatogram (using the same HPLC column) of a standard solution, which contained 4 pg of each of three different monosaccharides (i.e., the last three peaks shown are glucose, xylose and fiicose, in the order of increasing retention times). Part B shows the chromatogram obtained from hydrolysis of the partially purified (see text) microbubble surfactant (approximately 30 pg). All other experimental conditions were identical in the two cases, i.e., water eluent, 0.5 ml/min flow rate, 85°C, refractive index detector attenuation -2x. (Taken from ref. 322.)...

Subsequent experimental work in this laboratory was aimed at the systematic development of an efficient method for isolating the proteinaceous surfactants, which help stabilize natural microbubbles, from both commercial agarose powder and from forest soil samples collected locally. Successful isolation of this glycopeptide fraction was eventually achieved (ref. 322), and the results obtained from an extended program of chemical analysis, to further characterize and compare chemically these proteinaceous surfactants from both natural substances, are described below. 

Enzymatic degradation9 and slab gel electrophoresis of microbubble glycopeptide surfactant isolated from forest soil. (Taken from ref. 322.)... 

The isolation of the microbubble surfactant mixture from forest soil has been described in detail in preceding chapters. Quantitative examination of the surface properties of mono-molecular films of the isolated microbubble surfactant complex, at an air/water interface, were carried out using a modified Langmuir trough apparatus incorporating the surface tension method of Padday et al. (ref. 380). 

Isolation of microbubble glycopeptide surfactant from commercial agarose and forest soil... 

The proteinaceous (ref. 231) surfactants surrounding and stabilizing long-lived gas microbubbles, present in both carbohydrate (agarose) gels and forest soil extracts, have been successfully isolated from both of these natural sources. The isolation was first... 

The isolated proteinaceous surfactants, obtained from commercial agarose powder and forest soil extract, were found to have extremely similar total amino acid compositions. Table 4.2 summarizes the amino acid values obtained from four determinations for each of the two surfactant preparations it can be seen that the rather unusual amino acid ratios obtained (among 17 different amino acids) for the two separate cases closely resemble one another. Specifically, in both of these cases the relative amounts of the different amino acids identified (excluding tryptophan which is completely destroyed during acid hydrolysis) were as follows glycine serine > aspartic acid (and/or aspara-... 

The striking similarity between the proteinaceous surfactants obtained from agarose powder and forest soil extract was further demonstrated by sodium dodecyl sulfate/polyacrylamide-... 

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