title: Primary structure of sarcotoxin I, an antibacterial protein induced in the hemolymph of Sarcophaga peregrina (flesh fly) larvae.
abstract: The primary structure of sarcotoxin I, a potent bactericidal protein induced in the hemolymph of larvae of Sarcophaga peregrina (flesh fly), was investigated. Sarcotoxin I was a mixture of three proteins (sarcotoxins IA, IB, and IC) with almost identical primary structures. These proteins were found to consist of 39 amino acid residues and to differ in only 2-3 amino acid residues. The amino-terminal half of the molecules was rich in charged amino acids and was hydrophilic, whereas the carboxyl-terminal half was hydrophobic. It is suggested that the carboxyl-terminal half of sarcotoxin I penetrates into the bacterial membrane and that its amino-terminal half rich in basic amino acid residues interacts with acidic phospholipids in the bacterial membrane, resulting in perturbation of the membrane and loss of viability of the bacteria.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid; D004175:Diptera / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects; D006458:Hemolymph / Q000378:metabolism*; D007301:Insect Hormones / Q000302:isolation & purification* / Q000494:pharmacology; D019476:Insect Proteins; D010669:Phenylthiohydantoin; D013329:Structure-Activity Relationship
chemical_list: D000900:Anti-Bacterial Agents; D007301:Insect Hormones; D019476:Insect Proteins; D010669:Phenylthiohydantoin; C042572:sarcotoxin I protein, Sarcophaga peregrina