LL-37, Antimicrobial Peptide, human

Product Name: LL-37, Antimicrobial Peptide, human

Sequence One Letter Code: LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES

Sequence Three Letter Code: H-Leu-Leu-Gly-Asp-Phe-Phe-Arg-Lys-Ser-Lys-Glu-Lys-Ile-Gly-Lys-Glu-Phe-Lys-Arg-Ile-Val-Gln-Arg-Ile-Lys-Asp-Phe-Leu-Arg-Asn-Leu-Val-Pro-Arg-Thr-Glu-Ser-OH

Cas No: 154947-66-7

Chemical Formula:C205H340N60O53

Molecular Weight: 4493.6

Purity: 95%

Form: Lyophilized

Storage Conditions: - 20 °C

Research Area: Infection Disease Research

SMILES: CC[C@H](C)[C@@H](C(=O)NCC(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CC1=CC=CC=C1)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@@H]([C@@H](C)CC)C(=O)N[C@@H](C(C)C)C(=O)N[C@@H](CCC(=O)N)C(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@@H]([C@@H](C)CC)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CC(=O)O)C(=O)N[C@@H](CC2=CC=CC=C2)C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@@H](CC(=O)N)C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](C(C)C)C(=O)N3CCC[C@H]3C(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@@H]([C@@H](C)O)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CO)C(=O)O)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CO)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CC4=CC=CC=C4)NC(=O)[C@H](CC5=CC=CC=C5)NC(=O)[C@H](CC(=O)O)NC(=O)CNC(=O)[C@H](CC(C)C)NC(=O)[C@H](CC(C)C)N

IUPAC: (4S)-5-[[(2S)-6-amino-1-[[(2S,3S)-1-[[2-[[(2S)-6-amino-1-[[(2S)-1-[[(2S)-1-[[(2S)-6-amino-1-[[(2S)-1-[[(2S,3S)-1-[[(2S)-1-[[(2S)-5-amino-1-[[(2S)-1-[[(2S,3S)-1-[[(2S)-6-amino-1-[[(2S)-1-[[(2S)-1-[[(2S)-1-[[(2S)-1-[[(2S)-4-amino-1-[[(2S)-1-[[(2S)-1-[(2S)-2-[[(2S)-5-carbamimidamido-1-[[(2S,3R)-1-[[(2S)-4-carboxy-1-[[(1S)-1-carboxy-2-hydroxyethyl]amino]-1-oxobutan-2-yl]amino]-3-hydroxy-1-oxobutan-2-yl]amino]-1-oxopentan-2-yl]carbamoyl]pyrrolidin-1-yl]-3-methyl-1-oxobutan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]amino]-1,4-dioxobutan-2-yl]amino]-5-carbamimidamido-1-oxopentan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]amino]-1-oxo-3-phenylpropan-2-yl]amino]-3-carboxy-1-oxopropan-2-yl]amino]-1-oxohexan-2-yl]amino]-3-methyl-1-oxopentan-2-yl]amino]-5-carbamimidamido-1-oxopentan-2-yl]amino]-1,5-dioxopentan-2-yl]amino]-3-methyl-1-oxobutan-2-yl]amino]-3-methyl-1-oxopentan-2-yl]amino]-5-carbamimidamido-1-oxopentan-2-yl]amino]-1-oxohexan-2-yl]amino]-1-oxo-3-phenylpropan-2-yl]amino]-4-carboxy-1-oxobutan-2-yl]amino]-1-oxohexan-2-yl]amino]-2-oxoethyl]amino]-3-methyl-1-oxopentan-2-yl]amino]-1-oxohexan-2-yl]amino]-4-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-2-amino-4-methylpentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-carboxypropanoyl]amino]-3-phenylpropanoyl]amino]-3-phenylpropanoyl]amino]-5-carbamimidamidopentanoyl]amino]hexanoyl]amino]-3-hydroxypropanoyl]amino]hexanoyl]amino]-5-oxopentanoic acid

INCHIKEY: POIUWJQBRNEFGX-XAMSXPGMSA-N

INCHI:

InChI=1S/C205H340N60O53/c1-20-114(16)162(261-179(296)128(66-40-46-86-211)235-176(293)135(74-78-155(273)274)243-170(287)125(63-37-43-83-208)241-192(309)148(106-266)257-174(291)126(64-38-44-84-209)234-171(288)129(67-47-87-225-201(215)216)240-185(302)142(98-119-55-29-24-30-56-119)252-187(304)144(100-121-59-33-26-34-60-121)253-189(306)146(102-158(279)280)233-154(272)104-230-167(284)138(94-109(6)7)248-166(283)122(212)93-108(4)5)194(311)231-105-153(271)232-123(61-35-41-81-206)168(285)242-136(75-79-156(275)276)177(294)251-141(97-118-53-27-23-28-54-118)184(301)238-124(62-36-42-82-207)169(286)236-131(69-49-89-227-203(219)220)181(298)263-164(116(18)22-3)197(314)259-160(112(12)13)195(312)246-134(73-77-151(213)269)175(292)237-132(70-50-90-228-204(221)222)180(297)262-163(115(17)21-2)196(313)245-127(65-39-45-85-210)172(289)256-147(103-159(281)282)190(307)254-143(99-120-57-31-25-32-58-120)186(303)249-139(95-110(8)9)183(300)239-130(68-48-88-226-202(217)218)173(290)255-145(101-152(214)270)188(305)250-140(96-111(10)11)191(308)260-161(113(14)15)199(316)265-92-52-72-150(265)193(310)244-133(71-51-91-229-205(223)224)182(299)264-165(117(19)268)198(315)247-137(76-80-157(277)278)178(295)258-149(107-267)200(317)318/h23-34,53-60,108-117,122-150,160-165,266-268H,20-22,35-52,61-107,206-212H2,1-19H3,(H2,213,269)(H2,214,270)(H,230,284)(H,231,311)(H,232,271)(H,233,272)(H,234,288)(H,235,293)(H,236,286)(H,237,292)(H,238,301)(H,239,300)(H,240,302)(H,241,309)(H,242,285)(H,243,287)(H,244,310)(H,245,313)(H,246,312)(H,247,315)(H,248,283)(H,249,303)(H,250,305)(H,251,294)(H,252,304)(H,253,306)(H,254,307)(H,255,290)(H,256,289)(H,257,291)(H,258,295)(H,259,314)(H,260,308)(H,261,296)(H,262,297)(H,263,298)(H,264,299)(H,273,274)(H,275,276)(H,277,278)(H,279,280)(H,281,282)(H,317,318)(H4,215,216,225)(H4,217,218,226)(H4,219,220,227)(H4,221,222,228)(H4,223,224,229)/t114-,115-,116-,117+,122-,123-,124-,125-,126-,127-,128-,129-,130-,131-,132-,133-,134-,135-,136-,137-,138-,139-,140-,141-,142-,143-,144-,145-,146-,147-,148-,149-,150-,160-,161-,162-,163-,164-,165-/m0/s1

Source / Species: human

Conjugation: Unconjugated

Code Nacres: NA.26

Application: LL-37 is a human antimicrobial peptide belonging to the cathelicidin family and represents the first identified amphipathic α-helical antimicrobial peptide in humans. It plays a critical role in innate immunity by exerting broad-spectrum antimicrobial activity against bacteria, viruses, and fungi, particularly at sites of inflammation and tissue injury. LL-37 also modulates immune responses by influencing cytokine production, chemotaxis, and wound healing processes. The peptide demonstrates notable resistance to proteolytic degradation, contributing to its functional stability in biological environments. LL-37 is widely used in research on host defense mechanisms, inflammatory regulation, epithelial barrier function, and antimicrobial peptide biology, as well as studies examining its dual antimicrobial and immunomodulatory properties.

Current Research: LL-37 is a 37–amino acid cationic antimicrobial peptide derived from the C-terminal region of the human cathelicidin precursor protein hCAP18 (human cationic antimicrobial protein of 18 kDa). It is the only cathelicidin identified in humans and represents the first characterized endogenous amphipathic α-helical antimicrobial peptide in this species. Proteolytic cleavage of hCAP18 by serine proteases, such as proteinase 3 in neutrophils, releases the active LL-37 peptide at sites of infection, inflammation, and tissue injury. Structurally, LL-37 adopts an amphipathic α-helical conformation in membrane-mimetic environments. Its cationic charge and hydrophobic face enable selective interaction with negatively charged microbial membranes. This interaction promotes membrane destabilization, increased permeability, and ultimately microbial cell death. LL-37 exhibits broad-spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria, enveloped viruses, and certain fungi. Unlike many conventional antibiotics, its mechanism relies primarily on physical disruption of microbial membranes, contributing to a lower propensity for classical resistance development. Beyond direct antimicrobial effects, LL-37 functions as a multifunctional immunomodulatory peptide. It influences both innate and adaptive immune responses through interactions with host cell receptors and intracellular signaling pathways. LL-37 can modulate cytokine production, including regulation of pro-inflammatory mediators such as IL-6, IL-8, and TNF-α, depending on context and concentration. It also functions as a chemoattractant for immune cells, including neutrophils, monocytes, and T lymphocytes, thereby coordinating early inflammatory responses. LL-37 plays an important role in epithelial barrier defense. It is expressed by epithelial cells lining the skin, respiratory tract, gastrointestinal tract, and genitourinary mucosa. In addition to antimicrobial activity, LL-37 promotes wound healing by stimulating keratinocyte migration, angiogenesis, and re-epithelialization. These effects involve activation of signaling pathways such as EGFR transactivation and MAPK cascades. Consequently, LL-37 is considered both a host defense effector and a regulator of tissue repair processes. The peptide also participates in nucleic acid sensing and immune complex formation. LL-37 can bind extracellular DNA and RNA, facilitating their uptake by immune cells and modulating Toll-like receptor (TLR) signaling. This function is particularly relevant in inflammatory skin disorders such as psoriasis, where LL-37–nucleic acid complexes contribute to aberrant immune activation. Thus, LL-37 exhibits context-dependent effects, acting as either a protective antimicrobial agent or a contributor to chronic inflammatory pathology. A notable feature of LL-37 is its relative resistance to proteolytic degradation compared to many other antimicrobial peptides. Structural stability and interactions with membranes or extracellular matrix components help preserve its activity in biologically complex environments, including inflamed tissues rich in proteases. This stability enhances its functional persistence during infection or tissue damage. In research applications, LL-37 is widely used to study membrane–peptide interactions, antimicrobial peptide mechanisms, epithelial immunity, and inflammatory regulation. Experimental systems often include microbial killing assays, membrane permeability assays, cytokine profiling, chemotaxis assays, and wound-healing models. It also serves as a prototype for designing synthetic antimicrobial peptides and peptide-based immunomodulators. Overall, LL-37 is a central component of human innate immunity, combining broad-spectrum antimicrobial activity with diverse immunoregulatory functions. Its dual role in host defense and inflammation makes it a valuable tool for investigating epithelial barrier biology, immune signaling pathways, wound repair mechanisms, and the balance between protective immunity and inflammatory disease.