Limited proteolysis of glucose dehydrogenase from Bacillus megaterium by proteinase K

Glucose dehydrogenase from B. megaterium is subjected to proteolysis with proteinase K. Upon proteolysis the enzyme is inactivated and the polypeptide chain is cleaved into two distinct fragments. These components designated as K-protein and K-peptide have molecular masses of 26 000 and 3 000 Da, respectively. Under native conditions the K-protein and K-peptide remain associated and the tetrameric structure of the proteolytically modified enzyme is preserved. The K-protein and K-peptide were isolated and characterised. The cleavage occurs in the C-terminal region of the polypeptide chain. -Leu Ala decreases Ser-Ser-Glu is proposed as the cleavage site.