Antimicrobial Activity of Human Leukocyte Defensin HNP-4 Against Gram-negative Bacteria
type: CreativeWork
description: Human neutrophils (PMN cells) contain four peptides known as alpha (α)-defensins or HNP 1-4. The peptides have broad-spectrum antibiotic activity. HNP 1-3 are major neutrophil components. They differ by only one amino acid residue. HNP-4 is found in small amounts, and has a different sequence. HNP-4 purified from neutrophils was reported to be 100-times more active than HNP-1 against Escherichia coli, suggesting that HNP-4 plays a special role in helping neutrophils kill gram-negative bacteria. Activity of HNP-4 against gram-negative bacteria is of special interest because Aggregatibacter (Actinobacillus) actinomycetemcomitans (A.a.) and other periodontal pathogens are gram-negative. These bacteria are resistant to HNP 1-3. Defensin-resistance may contribute to the ability of these bacteria to cause disease. There have been no studies of HNP-4 activity against oral bacteria, because HNP-4 is found in small amounts and is difficult to purify. Recently, HNP-4 was chemically synthesized, making it possible to study its antibacterial activity. However, synthetic HNP-4 was reported to be no more active than HNP-1 against E. coli. Lipopolysaccharide (LPS) covers the surface of gram-negative bacteria. Each LPS molecule has three parts: a long carbohydrate chain (oligosaccharide) that is exposed on the cell surface, a short carbohydrate core, and lipid A that anchors LPS in the outer membrane. LPS on the bacterial cell surface may be the receptor for HNP-4 and other peptides that kill gram-negative bacteria. Our aims were to: (1) Compare the purity and physical properties of purified and synthetic HNP-4. (2) Compare activity of synthetic and purified HNP-4 against E. coli. (3) Determine whether synthetic HNP-4 binds to purified E. coli LPS. (4) Locate the HNP-4 binding site for synthetic HNP-4 on E. coli LPS molecules. (5) Measure activity of synthetic HNP-4 against A.a. (6) Compare binding of synthetic HNP-4 to LPS purified from E. coli and A.a. Results: (1) Purified and s…
abstract: Human neutrophils (PMN cells) contain four peptides known as alpha (α)-defensins or HNP 1-4. The peptides have broad-spectrum antibiotic activity. HNP 1-3 are major neutrophil components. They differ by only one amino acid residue. HNP-4 is found in small amounts, and has a different sequence. HNP-4 purified from neutrophils was reported to be 100-times more active than HNP-1 against Escherichia coli, suggesting that HNP-4 plays a special role in helping neutrophils kill gram-negative bacteria. Activity of HNP-4 against gram-negative bacteria is of special interest because Aggregatibacter (Actinobacillus) actinomycetemcomitans (A.a.) and other periodontal pathogens are gram-negative. These bacteria are resistant to HNP 1-3. Defensin-resistance may contribute to the ability of these bacteria to cause disease. There have been no studies of HNP-4 activity against oral bacteria, because HNP-4 is found in small amounts and is difficult to purify. Recently, HNP-4 was chemically synthesized, making it possible to study its antibacterial activity. However, synthetic HNP-4 was reported to be no more active than HNP-1 against E. coli. Lipopolysaccharide (LPS) covers the surface of gram-negative bacteria. Each LPS molecule has three parts: a long carbohydrate chain (oligosaccharide) that is exposed on the cell surface, a short carbohydrate core, and lipid A that anchors LPS in the outer membrane. LPS on the bacterial cell surface may be the receptor for HNP-4 and other peptides that kill gram-negative bacteria. Our aims were to: (1) Compare the purity and physical properties of purified and synthetic HNP-4. (2) Compare activity of synthetic and purified HNP-4 against E. coli. (3) Determine whether synthetic HNP-4 binds to purified E. coli LPS. (4) Locate the HNP-4 binding site for synthetic HNP-4 on E. coli LPS molecules. (5) Measure activity of synthetic HNP-4 against A.a. (6) Compare binding of synthetic HNP-4 to LPS purified from E. coli and A.a. Results: (1) Purified and s…
author: Hilal, George
keywords: Defensin, Cationic Antimicrobial Peptides, Periodontal Pathogens, Lipopolysaccharide
date published: 2008-05-01T07:00:00Z
date modified: 2026-07-24T05:00:11Z
provider: University of Tennessee Health Science Center
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Tennessee Health Science Center