Abstract: Isolation of the salivary basic glycoproteins CON-1 and CON-2 in high purity and without substantial loss of activity was achieved in a method utilizing two denaturing steps which limit proteolysis. Cloning of CON-1 and CON-2 from the PRB2 and PRB1 genes also provides a recombinant source of the proteins, which are useful inhibitors of alpha-glucosidases in the treatment of diabetes and in preventing retroviral infection. Subfragments of CON-1 and CON-2 having alpha-glucosidase inhibitory activity are identified which can be prepared synthetically in commercial-scale quantities.