July 2026 in “Preprints.org” In this study, incorporating a novel amino acid compound into a hair-straightening formulation improved humidity-resistant straightening and enhanced the surface and mechanical properties of hair fibers, including increased bending stiffness, reduced friction, and better shape retention under high temperature and humidity conditions.
100 citations
,
March 2006 in “Journal of biological chemistry/The Journal of biological chemistry” This study found that cystatin M/E strongly inhibits human cathepsin V and cathepsin L via distinct non-overlapping sites, suggesting an important role in human epidermal differentiation and hair follicle morphogenesis.
67 citations
,
December 1990 in “The journal of cell biology/The Journal of cell biology” This study identified two evolutionarily conserved ultra-high-sulfur keratin proteins in human and sheep hair follicles, which are specifically expressed in the hair cuticle during the late stages of fiber development.
66 citations
,
October 2002 in “Human molecular genetics online/Human molecular genetics” This study found that a nonsense mutation in the Cst6 gene of mice leads to severe skin and hair abnormalities, suggesting that cystatin M/E is crucial for epidermal function and viability.
40 citations
,
July 2015 in “Journal of Cellular Biochemistry” This study found that cysteine supplementation significantly increases keratin expression in human keratinocytes, and counteracts the negative impact of iron deficiency on keratin production by enhancing iron availability for cellular processes.