Antimicrobial Peptide in Human Blood Ultrafiltrate
One methods aimed at finding peptides and proteins, is the systematic analysis of polypeptides in human blood ultrafiltrate, which has proven to be successful. Liver-expressed antimicrobial peptide 1 (LEAP-1)/hepcidin (Code 4392-s) is an example of such, which elicits antimicrobial activity as well as some functions in iron homeostasis. Following LEAP-1, a new cationic peptide termed LEAP-2 has recently discovered by using this same method, the “peptide trapping” approach [Protein Sci., 12, 143 (2003)].
The isolated peptides have variable chain length with the deletion of the longest peptide, composed of 40 amino acid residues, at both the amino- and carboxyl-termini. Its disulfide arrangement was determined to be Cys1-Cys3 and Cys2-Cys4 (Cys numbering from the amino-terminus) by analyzing the molecular weight and sequence of the tryptic fragments. The cDNA cloning of LEAP-2 reveals the precursor of LEAP-2 to be a 77-residue peptide, in which the longest form corresponds to the residues between the positions of 38 and 77 in the precursor [prepro-LEAP-2(38-77)]. The primary structures of LEAP-2 of rhesus monkey, cow, pig, mouse, and guinea pig were also determined, and found to be highly conserved among these species. LEAP-2 mRNA is predominantly expressed in liver and small intestine.
Liver-Expressed Antimicrobial Peptide 2 (Human)
Met-Thr-Pro-Phe-Trp-Arg-Gly-Val-Ser-Leu- Arg-Pro-Ile-Gly-Ala-Ser-Cys-Arg-Asp-Asp- Ser-Glu-Cys-Ile-Thr-Arg-Leu-Cys-Arg-Lys- Arg-Arg-Cys-Ser-Leu-Ser-Val-Ala-Gln-Glu (Disulfide bonds between Cys17-Cys28 and Cys23-Cys33)
LEAP-2 [preproLEAP-2 (38-77)] exerts antibacterial activities against Gram-positive, Gram-negative bacteria, and yeast (IC50 value was around 5 μM against Saccharomyces. cerevisiae). Interestingly, the amino-terminally truncated form, prepro-LEAP-2 (44-77), has not affected the viability of the germs tested. This 40 amino acid residue peptide, LEAP-2, has been reported to be circulating in human blood. LEAP-2 should prove to be varuable in studying its role in self-defense in humans, as well as its role as an antibacterial peptide in the family of the well-established α-/β-defensins.
|4405-s||Liver-Expressed Antimicrobial Peptide 2 (Human)||0.1 mg vial||22,000|
|4392-s||Liver-Expressed Antimicrobial Peptide 1 (Human)||0.1 mg vial||18,000|