PROTEINS OF EPIDERMIS, RELATION TO AGING SKIN 335 the 10 M urea extract. The peak is quite symmetrical and the mobility of this protein at pH 7.0 was 3.4 cm. 2 volt -• sec. -• X 10 -•. Treatment of the insoluble proteins of isoelectric point of pH 6.3 with a 6 M urea solution for about two months resulted in its partial solution to yield proteins of isoelectric points of pH 4.5 and 5.5. The electrophoretic pattern of the fibrous protein is fairly symmetrical (Fig. 7) with a mobility at pH 7.0 of i Figure 6.--Electrophoretic pattern of the fibrous protein isolated from a 10 M urea ex- tract of epidermis, descending limb. Figure 7.--Electrophoretic pattern of the fibrous protein isolated from the insoluble proteins of isoelectric point of pH 6.3., de- scending limb. 5.0 cm? volt -x sec. -a X 10 -•. The pattern of the non-fibrous protein is not too symmetrical (Fig. 8) with a mobility at pH 7.0 of 4.9 cm? volt -a sec. -a X 10 • for this small peak. Solutions of the fibrous protein at concen- trations of 2 to 4.0 per cent were extremely viscous and easily formed fibers upon drying. Beef snout epidermis extracted with a 2 M urea solution did not form a clot following dialysis of the urea extract against distilled water. Isolation of the pH 5.5 and the pH 4.5 proteins in about equal amounts were obtained from the first extract (Chart III). The second and third 2 M urea extracts of the epidermis gave both proteins in lower amounts than were obtained from the first extraction. The figures given for the total amounts of the purified proteins in Charts I, II and III do not give the true relationships between the relative amounts of the fibrous and non-fibrous proteins in the epidermis because greater losses occurred during purification of the fibrous protein, because of its insolubility, than was found for the relatively more soluble non-fibrous protein.

336 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 8.--Electrophoretic pattern of the non-fibrous protein isolated from the insolu- ble proteins of isoelectric point of pH 6.3, descending limb. Figure 9.--Electrophoretic pattern of the non-fibrous protein isolated from a 0.5 M urea extract of epidermis, descending limb. TABLE 1--EFFECT OF THE EXTRACTION PROCEDURE ON THE MOBILITY OF THE FIBROUS PROTEIN O1• BEEr SNOUT EPIDERMIS - Extraction Procedure and Treatment , Mobility -- • Molar Tern- (cm. z volt -x Concen- pera- sec. -I X 10 5) tration Sample ture, Time, Descending of Urea No. øC. Days Nature of Extract Limb 10 1 0 10 6 2 20 67 6 3 0 7 6 3a 0 7 6 4 20 22 6 5 0 7 2 6 0 7 2 7 0 14 2 7 0 7 1 8 0 6 1 9 0 7 0.5 10 0 6 0.5 11 0 7 0.5 12 0 7 * Final solution of fibrous One extract of epidermis 3.4 Proteins ofisoelectric point 5.0 of pH 6.3 treated with a 6 M urea solution Supernatant after dialysis* 3.1 Residue from (3)** after 3.5 centrifugation a gel-like mass, redissolved Clot from dialysis (3)**, 3.2 rehomogenized in 6 M urea t Third extract of epidermis t 3.7, 5.0 .• of (3)** First extract of epidermis t 3.6 Third extract of epidermis 3.0 of (6) '}'** One extract of epidermis t 3.3 One extract of epidermis 3.2 One extract of epidermist 3.4 One extract of epidermis 3.9, 4.1, 4.2 One extract of epidermist 3.3 .6 One extract of epidermis 3 protein centrifuged for 1 hr. at 132,050 X gravity. ** These numbers refer to the Sample No. (column 2). t Final solution of fibrous protein centrifuged for 5 hr. at 132,050 X gravity. •t Mobility of a substance present in small amounts.