Inhibitory effects of alkylated Bence-Jones protein, k-type light chain, from urine of a patient with macroglobulinemia on gastric juice secretion and ulceration in rats.

Bence-Jones protein (BJP) was isolate from the urine of a patient with macroglobulinemia by salting out the ammonium sulfate, followed by chromatography on DEAE-cellulose column and gel filtration. This native BJP was identified as k-type light chain by immunoelectrophoresis and the native light chain showed almost no activity of inhibiting the gastric ulceration in pylorus-ligated rats. In contrast, reduction of the disulfide bond by 2-mercaptoethanol and alkylation of the thiol by iodoacetate in this native light chain resulted in significant inhibition of the gastric ulceration. The alkylated light chain also showed a significant inhibition of gastric juice secretion in pylorus-ligated rats.