Water-propanol Mixtures Research Articles

Effect of Propanol–Water Mixtures on the Reactivity of Wool Cystine

THIS communication shows that the concept of hydro-phobic bonds in interactions of soluble proteins1 can also be applied to water-insoluble fibrous proteins. It has been observed2,3 that lanthionine formation in wool at 65° C with sodium hydrogen carbonate or borate is much faster in mixed solvents than in aqueous solutions. This effect was not explained by the authors. It was also found by Atkinson, Filson and Speakman4,5 that it is more difficult to extend wool fibres in water alone than in saturated aqueous butanol. Now there is evidence that addition of organic solvents will tend to overcome the resistance of the hydrophobic interior of proteins to penetration by the aqueous solvent and thus may increase the reactivity of protein groups located in hydrophobic regions.

Action of Mixed Solvents on Wool

DURING the course of another investigation1 it was observed that the resistance of wool fibres to extension in water is greater than in butanol saturated with water. This surprising result, which has an important bearing on methods of determining the accessibility of wool to different reagents2, led to a study of the behaviour of wool fibres in mixtures of other primary alcohols and water, as well as in mixed solvents generally. Among the more interesting results so far obtained are those for n-propanol and water. After being calibrated by 30 per cent extension in distilled water at 22.2° C., merino wool fibres (5-cm. lengths) were released and allowed to stand in distilled water for 24 hr., before transference to the propanol–water mixture for 18 hr., followed by re-extension in the mixture at 22.2° C. The percentage change in resistance to 30 per cent extension (C.R.E.) was calculated from the two load/extension curves for each fibre, and each of the results in Table 1 is the average of the values for 10 fibres.