Block, R.J. 1939. The composition of keratins: the amino acid composition of hair, wool, horn, and other eukeratins. Journal of Biological Chemistry 128: 181-186, table 1. { copied = true; setTimeout(() => copied = false, 10000); }).catch(err => { console.error('Failed to copy:', err); }); " type="button" :class="copied ? 'bg-secondary border-secondary' : 'border-primary hover:bg-primary'" class="group lg:min-w-64 flex items-center justify-between gap-5 border border-solid px-5 py-2 cursor-pointer transition-colors"> PDF download available