Abstract
The acid saline extract (ASE) of rat submaxillary gland powerfully degrades 125I-glucagon. Besides 125I-glucagon, 125I-pancreatic polypeptide (PP) was also destroyed by ASE according to ordinary immunoassay system with trichloroacetic acid (TCA); but 125I-insulin was intact in the presence of ASE. Leupeptin and, to a lesser extent p-chloromercuriphenylsulfonic acid (PCMS) and N-ethylmaleimide, inhibited the destruction of 125I-glucagon or 125I-PP according to TCA method. These facts were also confirmed by gel filtration of the assay mixture. In the presence of leupeptin (0.4 mM) and PCMS (16 mM), there was no shift of the peak of labelled glucagon or PP. Thus ASE degrades not only 125I-glucagon but also 125I-PP, and the thiol proteinase inhibitor has a strong inhibitory effect on them.
