Abstract
It has been previously shown that the combined cystine of wool can be divided into fractions on the basis of reactivity with bisulfite, formaldehyde, and alkalis. The S-distribution and the reactivity of the combined cystine has been detd. for 15 keratins (including samples of hair, feathers and horn) and for 10 non-keratinous proteins. On the basis of reactivity to NaHSO3, the combined cystine of all the proteins tested showea 2 fractions.