title: Consequences of introducing a disulfide bond into an antibacterial and hemolytic peptide.
abstract: The effect of introducing a disulfide bridge between the N- and C-terminal ends on the structure and biological activities of the 13-residue linear peptide PKLLKTFLSKWIG(SPFK), which has both antibacterial and hemolytic activity, have been investigated. The terminal amino acids P and G in SPFK were replaced by cysteines to form a disulfide bridge. The linear peptides C(Acm)KLLKTFLSKWIC(Acm) and C(Acm) KLLKTFLSKWIC(Acm)-amide, where Acm is acetamidomethyl group, showed antibacterial activity but did not possess hemolytic activity unlike SPFK. Introduction of an S-S bridge resulted in enhanced hemolytic activity compared with SPFK. The hemolytic activity was particularly pronounced in the cyclic peptide CKLLKTFLSKWIC-amide. Circular dichroism studies indicate that the cyclic peptides tend to adopt distorted helical structures. The cyclic peptides also have a greater affinity for lipid vesicles, which could be the reason for the effective perturbation of the erythrocyte membrane.
authors.affiliation: Centre for Cellular and Molecular Biology, Hyderabad, India.
authors.forename: V
authors.initials: V
authors.lastname: Krishnakumari
authors.forename: A
authors.initials: A
authors.lastname: Sharadadevi
authors.forename: N
authors.initials: N
authors.lastname: Sitaram
authors.forename: R
authors.initials: R
authors.lastname: Nagaraj
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D002942:Circular Dichroism; D004220:Disulfides / Q000737:chemistry*; D006461:Hemolysis / Q000187:drug effects*; D008567:Membranes, Artificial; D008969:Molecular Sequence Data; D010455:Peptides; D011487:Protein Conformation
chemical_list: D000900:Anti-Bacterial Agents; D004220:Disulfides; D008567:Membranes, Artificial; D010455:Peptides