Protein Description Sequence Coverage (%) #Peptides #Unique peptides Artefact Keratin 1 (Fragment) 1 1 1 Histone H2B type 1-M 1 1 1 Histone H2B 1 1 1 Histone H2B type 1-H 1 1 1 Histone H2B 1 1 1 Histone H2B type 1-L 1 1 1 HIST1H2BC protein 1 1 1 Histone H2B type 2-F 1 1 1 Spectrin beta chain 1 2 2 Mucin-2 1 2 2 Protein 4.1 1 2 2 EPB41 protein 1 2 2 Collagen type XI alpha 1 1 1 1 Collagen type XI alpha 1 1 1 1 Keratin-associated protein 4-1 1 1 1 Neurexin-3-beta 1 1 1 Conserved oligomeric Golgi complex subunit 1 1 1 1 Conserved oligomeric Golgi complex subunit 1 1 1 1 Keratin-associated protein 4-1 1 1 1 Carboxy-terminal domain RNA polymerase II polypeptide A 1 1 1 ADAMTS-like protein 3 1 1 1 Uncharacterized protein 1 1 1 Appendix 1 Continued HAIR SHAPE PROTEOMICS 267

Role of Redox Metals in Color Formation in a Hair Colorant JENNIFER M. MARSH, ROBIE L. LUCAS, CHRIS COWANS, and SHANE WHITAKER , The Procter & Gamble Company Mason, Ohio, 45040 (J.M., R.L., C.C., S.W.) Accepted for publication January 13, 2021. Synopsis The objective of this work was to identify if low levels of redox metals such as copper would accelerate color formation on hair and to understand the consequent impact on initial color formation and color fade. Kinetics of color formation with oxidative dyes in solution in the presence of varying concentrations of copper ions were assessed via imaging and color measurements. Color uptake on hair and color fade were measured with a spectrophotometer, and copper levels in hair were measured with inductively coupled plasma atomic spectroscopy after hair digestion. In this work, the role of redox metal ions such as copper and iron on accelerating rates of oxidative dye formation was demonstrated. Kinetics of dye formation were measured in solution for three dye couples—p-phenylene diamine (PPD) plus resorcinol, PPD plus 5-amino-2-methylphenol (AHT), and 4,5-diamino-1-(2-hydroxyethyl) pyrazole sulfate (HDAP) plus AHT— in a solution that also contained ammonium hydroxide and hydrogen peroxide at pH 10. Low levels of copper were added at a concentration range from 0.01 μg/g to 0.1 μg/g and the rate of color formation measured over 2 h. All th ree dye couples showed signifi cant color acceleration that increased with increasing levels of copper. A mechanism where initial oxidation of primary intermediate PPD or HDAP is accelerated is proposed. This mechanism is demonstrated to become important when trace levels of copper are in hair and a hair colorant added. Color formation is accelerated outside versus inside hair, and ultimately, color uptake is reduced after the colorant is rinsed off hair. Noticeable color fade versus the starting hair color is also increased. T his work provides evidence for the role of copper ions in color formation in hair and strategies to reduce copper levels in hair using a chelant such as histidine in a shampoo or conditioner before coloring. I N TRODUCTION H air colorants constitute a signifi cant category in the cosmetics market—it is estimated that more than 70% of women in the developed world have used hair color, and a large proportion of those do so regularly. Although each woman may have a very individual rea- son for coloring her hair, covering gray can be considered a universal key motivator. Other desired performance aspects include enhancing the existing color, wanting a different color from the on e given to oneself by nature, or achieving a more striking looking appearance. The most widely used products in the colorant category are Permanent Level 3 colorants that consist of a combination of an alkalizer (typically ammonia, but ethanolamine is also Address all correspondence to Jennifer Marsh at marsh.jm@pg.com. J. Cosmet. Sci., 72, 268–278 (May/June 2021) 268