470 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table VI Preparation of Hair Containing Unequal Amounts of Ker-CySH and Ker-CySSOa- Condition Treatment Ker-CySH = Ker-CySSO•- Ker-CySH Ker-CySSO•- Ker-CySH Ker-CySSO•- Ker-CySSO•- only Ker-CySH only Bisulfite Thioglycolate followed by bisulfite Bisulfite-tetrathionate followed by bisulfite Bisulfite-tetrathionate Thioglyeolate Table VII Analysis of Hair Treated with Sulfite Systems a Immersion Ker-CySSOa- Time meq SH/g meq/g meq/g pH (hours) MNP• MNP• MNP3 Theor * Calc • Theor b Calc" 3.5 1.25 0.70 0.32 0.15 0.35 0.35 0.35 0.36 4.5 1.25 0.88 0.20 0.10 0.44 0.44 0.44 0.44 5.5 1.25 0.94 0.10 0.08 0.47 0.50 0.47 0.44 6.5 1.00 0.81 0.01 0.00 0.40 0.40 0.40 0.41 7.5 1.00 0.50 0.19 0.09 0.25 0.25 0.25 0.26 8.5 2.00 0.36 0.19 0.09 0.18 0.18 0.18 0.18 "1.0M NH4HSO•-3.0M urea, 32 ø C, 50:1 bath ratio. b %MNP•. • MNP• + ¾•(MNP•-MNP•). a MNP•-[MNP• + ¾•(MNP•-MNP•)]. The first analysis was performed on the bisulfite-treated hair where the CySSOa- to CySH ratio would be expected to be one. These results are summarized in Table VII for hair treated with bisulfite at pH's ranging from 3.5 to 8.5. The data clearly show that the CySSOa- to CySH ratio for hair treated in this broad pH range is one. These results are totally consistent with the general cystine-bisulfite reaction mechanism and reflect the pH dependence of the cystine-bisulfite equilibrium (8). It also shows that the analytical method is applicable to hair treated with bisulfite at higher pH's than previously observed. The method was next applied to hair containing excess cysteinyl residues. The results are described in Table VIII. For hair treated with thioglycolate followed by bisulfite, there is obtained a total CySSOa- content of 0.17 meq/g and a CySH content of 0.34 meq/g. For hair containing excess CySSOa- residues, the treatment of hair with bisulfite-tetrathionate followed by bisulfite was considered. The data are

CYSTEINYL AND S-SULFOCYSTEINYL RESIDUES 471 Table VIII Analysis of Hair Treated •vith Thioglycolate (TGA)" Followed by Bisulfite b meq SH/g MNP• of TGA treatment 0.19 MNP (after TGA and bisulfite treatment) MNPi 0.53 MNP., 0.26 MNP., 0.06 Ker-CySSO3- (calculated •) 0.17 Ker-CySSO3- (found) 0.19 Ker-CySH (found a) 0.35 • 1.0-hour immersion in 0.15N ammonium thioglycolate, pH 9.2, 32øC, 50:1 bath ratio, 30-min •vater rinse under N, b 15-rain immersion in 0.5M NH4HSO3-1.0M urea, pH 6.5, 32øC, 50:1 bath ratio. • Ker_CySSO•- (calculated): [MNP•-MNP• øf TGA treatment 1 2 ' a Ker-CySH (found) = [MNP• (after TGA and bisulfite treatment)-Ker-CySSO,- (found)]. Table IX Analysis of Hair Treated •vith Bisulfite-Tetrathionate • Followed by Bisulfite • meq SH/g 0.26 MNP• of bisuhqte-tetrathionate treatment MNP (after bisulfite-tetrathionate treat- ment and bisulfite treatment) MNPi MNP, MNP, Ker-CySSO•- (calculated *) Ker-CySSO.•- (found) Ker-CySH (found a) 0.61 0.32 0.26 0.44 0.40 0.21 10-min immersion in 1.0M NH•HSO•-4.0M urea-4.0M tetrathionate, pH 8.0, 50:1 bath ratio, 32 ø C, followed by 30-min immersion in water. 15-min immersion in 0.5M NH•HSO•-i.5M urea, pH 6.5, 50:1 bath ratio, 32øC. Ker-CySSO•- (calculated) = ¾2 [MNP• + MNP• of bisulfite-tetrathionate]. Ker-CySH (found) = [MNP•-Ker-CySSO.•- (found)]. reported in Table IX. Again there is seen consistent behavior. The CySSOa- content is 0.44 meq/g while the CySH content was found to be 0.21 meq/g. For hair contai•fing S-sulfocysteinyl residues only as previously discussed (Table V), evidence of only CySSOa- residues is observed no CySH resi- dues can be determined. Similarly, for hair treated with thioglycolate only (Table IV) cysteinyl residues are observed.