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.

PROTEINS OF EPIDERMIS, RELATION TO AGING SKIN 337 Beef snout epidermis extracted with 0.5 and 1.0 M urea solutions did not yield a clot in the dialysis sac following dialysis against distilled water. Figure 9 shows an electrophoretic pattern of the non-fibrous protein from a 0.5 M urea extract. The peak is quite symmetrical and it had a mobility of 3.4 cm. 2 volt -x sec. -1 ( 10 5. There were also present two other minor components with mobilities of 4.8 and 7.4 cm? volt -x sec. -1 X 10 5. The fibrous protein from one of the 0.5 M urea epidermal extracts had an dec- trophoretic pattern with three large peaks (Fig. 10) of mobilities of 3.9, 4.1 and 4.2 cm? volt -x sec. -x X 10 -5. Figure 10.--Electrophoretic pattern of the fibrous protein isolated from a 0.5 M urea extract of epidermis, descending limb. The mobilities of the fibrous protein extracted from epidermis under vari- ous conditions are given in Table 1. The mobility of this protein at pH 7.0 appears to be independent of the concentration of urea employed for its extraction. Only the mobility of the protein isolated from the urea treated proteins of isoelectric point of pH 6.3 is significantly higher (mobility of $.0 cm? volt -• sec.-• X 10 -5) than that given by this protein obtained by the other extraction procedures. The insolubility of the fibrous protein necessitated redispersion and resolution in urea several times during the purification process, and such treatment must produce a protein of different composition than is found originally present in epidermis. Other physico- chemical techniques may show some differences in the properties of the fibrous protein as a function of the urea concentration employed for its extraction.