SgI-29 is a newly characterized antibacterial peptide derived from human semenogelin I. Using SgI-29 as model, 4 peptides with different length were synthesized. Physico-chemical characteristics and structure prediction of SgI-29 and its derived peptides were analyzed by software packages and helix-wheel plot. The antibacterial activities of SgI-29 and its derived peptides against Escherichia coli
ATCC 25922 and Pseudomonas aeruginosa
ATCC 27853 were determined. The structure-function relationship of SgI-29 and its derivatives was analyzed. Our results indicated that SgI-22 has the strongest antibacterial activities against the tested bacteria among the synthetic peptides and might be used as a good model for the structure optimization.