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Vol. 6i PARTIAL HYDROLYSIS OF ELASTIN 21 p-proteins were separated by repeated precipitation of the coacervate at 600; osmotic-pressure determinations on the preparations gave a mean molecular weight of 67000 for the a-protein and 5500 for the p-protein.The a-protein had ash 0.03%. Analysis by combustion (Weiler and Strauss, Oxford) gave C, 52-9; H, 7-4; N, 16.5%. The ,-protein had ash 0-28; C, 52-4; H, 7-75; N, 16-6 % (analyses corrected for ash). METHODSAmino acid analy8i8 of ela8tin and the two derived protein8 The procedure adopted for the separation and estimation of the amino acids was that of . The two samples of elastin powder, and the standard preparations of a-and ,B-protein were hydrolysed with acid and chromatographed under identical conditions. For hydrolysis, the protein (500 mg.) was mixed with 6N-HC1 (50 ml.) and the mixture refluxed for 24 hr. Hydrochloric acid was then removed by repeated evaporation in vacuo, and the syrup made up to 50 ml. with distilled water. Portions were then taken for determination of N (Kjeldahl). Equal volumes of the hydrolysate and sodium citrate buffer (0.1 M, pH 3.42) were then mixed, and 1 ml. of the buffered solution was applied to the columns. The weight of protein equivalent to the amino acid mixture applied to the column was calculated from the nitrogen content of the hydrolysate. The management of the columns exactly followed the procedure given by .Arginine, lysine and histidine were estimated using the short (15 cm.) column of Moore & Stein. Hydroxyproline was estimated in separate experiments in which the 100 cm. column was first equilibrated with a sodium citrate buffer of slightly lower pH (pH 3.04). The column was then developed with a further quantity of pH 3-04

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