Synthesis and cross-linking in the structure and growth of hair keratins

Abstract

In dealing with the biochemical mechanisms associated with hair growth, it is important to delineate areas where our knowledge is lacking. Indeed, despite enormous literature that has accumulated over many years, the hair follicle is still a “black box” in terms of what we know of molecular events in hair growth. Regions of the follicle under discussion herein are shown in Figure 4-1 in the color section. At a rate of growth of approximately 300 μm per day, a hair cell would take 5 days to migrate from the bulb region and emerge as a keratinized cell. At the end of the period of keratin synthesis (indicated in red) the -SH content of the proteins is rapidly lowered to the level (approximately 30 μmoles/g) found in the keratinized hair, by oxidation to disulfide bonds. The oxidized state is reached over a period of 6–12 hours.