Description

LL-37 10mg

Human Cathelicidin Antimicrobial & Host-Defense Peptide

LL-37 is a synthetic version of the naturally occurring human cathelicidin antimicrobial peptide. It is a 37-amino-acid, positively charged peptide that forms an amphipathic alpha-helical structure under appropriate biological conditions.

LL-37 is one of the most extensively studied human antimicrobial peptides because its biological activity extends well beyond direct antimicrobial effects. Research has identified roles involving innate immune defense, bacterial membrane disruption, inflammatory signaling, immune-cell recruitment, endotoxin interactions, biofilm biology, angiogenesis, epithelial repair, and wound-healing mechanisms.

In humans, LL-37 is produced from the precursor protein hCAP18, encoded by the CAMP gene. hCAP18 is expressed by several immune and epithelial cell populations and can be enzymatically processed to release biologically active LL-37.

Because of its position at the intersection of antimicrobial defense, immune signaling, and tissue repair, LL-37 has become an important experimental compound for researchers investigating host-defense mechanisms and the relationship between infection, inflammation, and tissue regeneration.

Molecular Profile

Compound: LL-37
Classification: Cathelicidin antimicrobial peptide / host-defense peptide
Peptide length: 37 amino acids
Molecular mass: Approximately 4.49 kDa
Structure: Cationic, amphipathic peptide with substantial alpha-helical character under membrane-associated conditions
Natural precursor: hCAP18
Gene: CAMP
Species of origin: Human
Form: Lyophilized research peptide
Research status: Experimental

LL-37 derives its name from the two leucine residues at its N-terminus—LL—and its length of 37 amino acids.

A Natural Component of Human Innate Immunity

LL-37 is part of the body’s innate immune-defense system.

Unlike adaptive immunity, which develops highly specific responses to particular pathogens, innate immunity provides an immediate first-line defense against potentially harmful microorganisms.

LL-37 is naturally expressed in several tissues and cell types, including:

• Neutrophils
• Monocytes
• Macrophage-associated immune systems
• Skin and keratinocytes
• Respiratory epithelium
• Gastrointestinal epithelium
• Other epithelial surfaces exposed to microorganisms

This distribution places LL-37 at many of the biological interfaces where the body encounters bacteria and other environmental microorganisms.

Antimicrobial Research

The best-established research area for LL-37 is its interaction with microorganisms.

LL-37 carries a strong positive charge while many bacterial membrane surfaces contain negatively charged components.

This electrostatic difference allows LL-37 to associate with microbial membranes.

Once associated with the membrane, its amphipathic structure allows portions of the peptide to interact with membrane lipids. Experimental research indicates that LL-37 can disturb membrane organization and permeability.

Researchers have investigated activity against numerous microorganisms, including models involving both:

Gram-positive bacteria

and

Gram-negative bacteria

Experimental studies have additionally examined LL-37 in fungal and viral systems.

The presence of antimicrobial activity in laboratory models does not establish LL-37 as a clinically effective treatment for infection.

Bacterial Membrane Research

One particularly important area of LL-37 research concerns membrane permeabilization.

LL-37 can transition toward an alpha-helical structure when interacting with lipid membranes.

Its structure contains both hydrophobic and hydrophilic surfaces. This amphipathic configuration allows the molecule to associate with lipid bilayers and alter membrane organization.

Several models have been proposed to explain antimicrobial-peptide membrane disruption, including pore formation and membrane destabilization.

This makes LL-37 useful for laboratory investigation of:

• Peptide-membrane interactions
• Bacterial membrane integrity
• Membrane permeability
• Host-defense peptide structure
• Antimicrobial resistance mechanisms
• Structure-activity relationships

Lipopolysaccharide — LPS Research

LL-37 has also been extensively investigated for interactions with lipopolysaccharide (LPS).

LPS is an important structural component of the outer membrane of Gram-negative bacteria and is capable of producing strong inflammatory signaling in mammalian systems.

LL-37 can bind LPS in experimental models.

Consequently, researchers have investigated whether LL-37 can alter biological responses associated with bacterial endotoxin exposure.

This creates an important distinction:

LL-37 does not function exclusively through direct microbial membrane disruption.

It can also interact with microbial molecules and host immune pathways, which is one reason LL-37 is frequently described as a host-defense peptide rather than simply an antimicrobial peptide.

Biofilm Research

LL-37 has attracted considerable attention in biofilm research.

Biofilms are organized communities of microorganisms surrounded by an extracellular matrix. Biofilm formation can substantially change microbial physiology and can make microorganisms considerably more difficult to study and control than free-floating planktonic organisms.

Experimental studies have investigated LL-37’s ability to interfere with different stages of bacterial biofilm biology.

This has made LL-37 particularly interesting for laboratory research involving:

• Biofilm formation
• Bacterial attachment
• Biofilm architecture
• Microbial communication
• Host-defense responses to biofilms
• Chronic wound microbiology

Biofilm research remains one of the more interesting experimental applications of LL-37.

Immunomodulatory Research

One of the most important characteristics of LL-37 is that it is not simply antimicrobial.

LL-37 interacts with host cells and can influence immune signaling.

Research has examined LL-37 in connection with:

• Chemotaxis
• Neutrophil activity
• Monocyte recruitment
• Cytokine signaling
• Innate immune activation
• Inflammatory regulation
• Cellular membrane signaling