C-Terminal Propeptide of BKA has a Protease Sensitive Structure Without any Inhibitory Effect on BKA

In our previous study, we compared the two αamylase enzymes from Bacillus sp.KR8104, BKA∆(N44) and BKA∆(N44C193) which is the secreted form of it. The results indicated that the presence of 193 amino acids propeptide in the Cterminal of BKA∆(N44) changed its enzymatic parameters like an uncompetitive inhibitor in comparison to BKA∆(N44C193). In the present study, we cloned the DNA sequence of BKA∆(N44) which codes the 193 amino acids propeptide in its Cterminal and the effect of this fragment as an inhibitor on BKA∆(N44C193) was investigated. We also studied the possible foldase activity of the propeptide in BKA∆(N44C193). Protease sensitivity of Cterminal 193 amino acid propeptide, BKA∆(N44) and BKA∆(N44C193) was compared in order to explain why  BKA∆(N44C193) is the only secreted form of αamylase in the culture medium of Bacillus sp.KR8104. Circular dichroism indicated that the secondary structure of the Cterminal is mostly beta sheeted. At the end we proposed a possible regulatory role for the Cterminal propeptide of BKA.