ISOLATION AND ALPHA-AMIDATION OF THE NON-AMIDATED FORM OF CECROPIN-D FROM LARVAE OF BOMBYX-MORI

Two forms of cecropin D, an antibacterial protein, were isolated from larvae of the silkworm, Bombyx mori, immunized with Escherichia coil. One was the mature form and the other seemed to contain a glycine resi due at its C-terminus. The latter was converted into the mature form i n vitro by peptidylglycine alpha-amidating enzymes from horse serum an d the result clearly demonstrates that this protein is the precursor o f cecropin D. The mature form had 4- to 5-fold higher antibacterial ac tivity against E. coil or Acinetobacter sp., suggesting that the amida tion is important for full expression of antibacterial activity.