WATER-SOLUBLE ELASTIN AS A COSMETIC MATERIAL 19 Figure 4. Water contents of cells treated with HAPA-elastin, and fractions 1 and 2. Water content was 49.4% ± 10.1% without HAPA-elastin (i.e., only D.W.), which was used as the reference (unshaded bar). Water contents of cells treated with the respective concentrations of (a) HAPA-elastin, (b) fraction 1, and (c) fraction 2. Data are presented as mean ± standard error of the mean. *p 0.05.

JOURNAL OF COSMETIC SCIENCE 20 Characteristically, the ratio of Des and Ide residues to total residues in HAPA-elastin is 4:1,000 (Table I). As a guideline for evaluating elastin, the Japan Health and Nutrition Food Association has stated that, the standard value of the total content of Des and Ide in pure elastin should exceed 0.2% per molar ratio (18). In this study, the total content of Des and Ide was 0.4% per molar ratio. It was within the accepted range and confi rmed that HAPA-elastin was of high purity, and was effi ciently prepared from the pig aorta. Although several elastins sold on the market usually show little coacervation property, this study confi rmed the coacervation ability of HAPA-elastin. In addition, HAPA-elastin has a wide molecular weight range, consisting of large-molecular-weight polypeptides and small fragments. It is considered that coacervation results from the intramolecular and intermolecular hydrophobic interactions within a sample (19,20). Amino acid analy- sis showed that HAPA-elastin contained many hydrophobic amino acids such as Gly, Ala, Val, and Pro. These hydrophobic amino acids accounted for more than 81.5% of the total amino acid content of HAPA-elastin. During the separation process, the elastin solution separates into two layers. One is the supernatant, which is a solution of soluble peptides (low-molecular-weight elastin). The other is the precipitate, which comprises coacervate aggregates of elastin (high-molecular-weight elastin) produced during the heating pro- cess (21,22). Fraction 1 accounted for 89.3% of the coacervate yield from HAPA-elastin and showed an apparent difference in molecular weight (Figure 3b) as compared to HAPA-elastin. Fraction 1 lacked high-molecular-weight proteins, whereas fraction 2, which accounted for 10.7% of the yield, contained a relatively higher amount of high- molecular-weight proteins (44,000–67,000 Da) (Figure 3c). HAPA-elastin is a useful Figure 5. Rate of tyrosinase inhibition by HAPA-elastin and fractions 1 and 2. Tyrosinase activity was 100% when D.W. was added to the cells as the control. Data are presented as mean ± standard error of the mean. *p 0.05.