Comparative action of reducing agents on fibrillar human bronchial mucus under dissociating and non-dissociating conditions.

Gel=like or fibrillar human bronchial mucus was reduced with mercaptoethanol under dissociating and non-dissociating conditions. Bronchial mucus was solubilized in both conditions; but reduction in phosphate buffer induced more extensive depolymerization of mucus glycoproteins than obtained under reduction in guanidine. Moreover, mucins prepared by reduction in non-dissociating conditions contained less amino acid and more carbohydrate. These data strongly suggest that reduction under non-dissociating conditions does not act only on disulfide bridges but also induces the activation of a mucolytic enzymatic system. They also would explain some of the discrepancies observed in the molecular weight determination and chemical composition of human bronchial mucus glycoproteins purified after reduction of gel-like mucus under different conditions.