Individual substitution analogs of Mel(12-26), melittin's C-terminal 15-residue peptide: their antimicrobial and hemolytic actions.
Residues 1-9 of M(12-26) (GLPALISWIKRKRQQ-NH2), the C-terminal 15-residue segment of melittin, were substituted individually to change the hydropathicities in these positions. Antimicrobial and hemolytic activities of these peptides were determined. The results showed increased antimicrobial activities with increased hydrophobicities at almost all the positions studied. The effects at positions 2, 5, 8 and 9 were significant while the effects at the other positions were small. These two groups of residues were located on the opposite faces of the alpha-helix. In other words, the hydrophobicities of the two faces were favorable, but one face (the more favorable face) contributed more to the antimicrobial activities than the other (the less favorable face). The hydrophobicity, not the amphipathicity, seems to be crucial for antimicrobial activity. In contrast, the hydrophobicity of one face was favorable but the other was unfavorable for the hemolytic activity, indicating that the amphipathicity may be important for hemolysis. Interestingly, the more favorable face for antimicrobial activity was located opposite to the favorable face for hemolytic activity, indicating the direction of the hydrophobic face for the antimicrobial activity and direction of the amphipathicity for the hemolytic activity were also important.
Institute of Polymer Chemistry, State Key Laboratory of Function Polymer Materials for Adsorption and Separation, Nankai University, Tianjin 300071, PR China. yanhs@nankai.edu.cn
Husheng
H
Yan
Shunzi
S
Li
Xuejun
X
Sun
Huaifeng
H
Mi
Binglin
B
He
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008555:Melitten / Q000031:analogs & derivatives* / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology; D013329:Structure-Activity Relationship
D000900:Anti-Bacterial Agents; D010446:Peptide Fragments; D008555:Melitten