caP4: A 2.97 KDa Cationic Antibacterial Peptide from Curcuma pseudomontana L

The present investigation reports the sequence of a 2.97KDa low molecular weight, cationic antibacterial peptide, caP4 isolated from wild variety of turmeric, Curcuma pseudomontana L. (Zingiberaceae). The rp -HPLC of 80% saturated ammonium sulphate protein precipitate showed four peaks labelled P1, P2, P3 and P4. The peak fraction, P4 eluted at 39.73 min showed 63.47% and 43.27% inhibition against E. coli and S. aureus respectively. The P4 was found to be stable at − 20 °C to 65 °C, in pH from 7.0 to 10.0 and retained antibacterial activity when treated with proteases. The MIC of P4 varied for different bacterial strains between 10 and 30 mg/L. Biofilm formation of P. aerugenosa and S. aureus was declined to 90% and 50% respectively at 20 µg of P4. The P4 on UPLC-MS yielded single major peak (with retention time of 1.98 min). The peak fraction was pooled and analysed using ESI-MS/MS, showing peptide masses ranging from 400 to 1800 Da. Further, Tof MS/MS-ESI of two intense peak yielded the sequences ASSCKPS (mass 1.16KDa) and ASSKWVAPSEW (mass 1.81 kDa) with a total mass of 2.97KDa, designated as caP4 (cationic peptide of Peak 4) having a net charge of +1 and hydrophobicity ranging from 18 to 22%. The above results show that caP4 could possibly be used as antibacterial peptide with significant therapeutic index.