Plant Antimicrobial Peptides as Potential Anticancer Agents

Figure 2

Alignment of amino acid sequences from cytotoxic cyclotides. (a) The cysteine residues present in all sequences and relevant to the classification are indicated in red letters. The asparagine residues present in all sequences and relevant to the cyclization process are indicated in blue letters. (b) Amino acid sequence alignment of cycloviolacins O2 and 13. The replacement of serine by alanine (shaded in green) increases the hemolytic effect by more than 3-fold. (c) Amino acid sequence alignment of Viphi G, Viphi E, Viphi F, Viphi A, and Viphi D cyclotides. Shaded in yellow are the sequences with no-toxic effects; the red arrows indicate the residues with specific variations. The sequences included in the alignment were cliotides T1 (GenBank accession AEK26402), T2 (GenBank accession AEK26403), T3 (GenBank accession AEK26404), and T4 (GenBank accession AEK26405) from Clitoria ternatea, cycloviolacins O2 (GenBank accession P58434) and O13 (GenBank accession Q5USNB) from Viola odorata, Vibi D (GenBank accession P85242), Vibi G (GenBank accession P85245), and Vibi H (GenBank accession P85246) from Viola biflora, Varv A (GenBank accession Q5USN7) and Varv F (GenBank accession 3E4H_A) from Viola odorata, Mram 8, Viphi A, Viphi D, Viphi E, Viphi F, and Viphi G [73] from Viola philippica, and Vaby D [55] from Viola abyssinica.

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