Helical Twist Direction in the Macrofibrils of Keratin Fibres Is Left Handed

The study reanalyzed existing data and re-imaged samples to conclude that the helical twist in macrofibrils of keratin fibers in mammalian hair was consistently left-handed. This conclusion was drawn from reviewing 644 double-twist macrofibrils across 41 tomograms from studies conducted between 1999 and 2011. The research found that all macrofibrils within each tomogram shared the same handedness, with 12 tomograms showing only left-handed macrofibrils and 29 showing only right-handed ones. The study suggested that previous reports of mixed handedness might have been due to data artifacts. The findings have implications for understanding the structure and function of keratinized macrofibrils in hair.