Identification and purification of an antimicrobial peptide from ziziphus jujuba

In this study، an antibacterial and antifungal peptide named; Snakin-Z was identified and purified from the fruit of Zizyphus jujuba، using gel filtration and reverse-phase high-performance liquid chromatography (RP-HPLC). This peptide is composed of 31 amino acids with the sequence of: CARLNCVPKGTSGNTETCPCYASLHSCRKYG. The molecular weight of this peptide was found to be 3308. 823 Da. By multiple sequence alignment، Snakin-Z was seen to have highest similarity to antimicrobial peptide (AMP) Snakin-2، but this peptide shows no sequence homology to any AMP in the peptide database. Studies have shown that Snakin-Z has potent antimicrobial activity both against Gram-positive and Gram-negative bacteria as well as fungi. Minimum inhibition concentration (MIC) value of this peptide is suitable for potent antimicrobial peptides. Significant antifungal activity of Snakin-Z was seen to have a greatest effect on Phomopsis azadirachtae with the MIC value of 7. 65 µg/ml; While، among bacterial strains، Staphylococcous aureus was investigated to be the most resistant one with the MIC of 28. 8 µg/ml. Human red blood cells showed good tolerance while exposed to the Snakin-Z. Regarding its antimicrobial activities and its effect against various pathogens and no hemolytic activity، we believe that Snakin-Z is appropriate candidate for the therapeutic applications in the future.