The BLV-miRNAs pathway of BLV inhibits the expression of Lactoferrin, Lactoperoxidase, Alpha-lactalbumin and Beta-lactoglobulin proteins.

Bovine leukemia virus (BLV) is a widespread virus that decreases milk production and quality in dairy cows. As crucial components of BLV, BLV-encoded microRNAs (BLV-miRNAs) affect BLV replication and may impact the synthesis of Lactoferrin (LTF), Lactoperoxidase (LPO), Alpha-lactalbumin (alpha-LA), and Beta-lactoglobulin (beta-LG). In this study, we investigated the targeting relationship between BLV-miRNAs and LTF, LPO, alpha-LA, and beta-LG in cow's milk. Additionally, we investigated the possible mechanisms by which BLV reduces milk quality. The results showed that cow's milk had significantly lower levels of LTF, LPO, and alpha-LA proteins in BLV-positive cows than in BLV-negative cows. BLV-△miRNAs (miRNA-deleted BLV) enhanced the reduction of LPO, alpha-LA, and beta-LG protein levels caused by BLV infection. Multiple BLV-miRNAs have binding sites with LTF and LPO mRNA; however, only BLV-miR-B1-5 P has a targeting relationship with LPO mRNA. The results revealed that BLV-miR-B1-5 P inhibits LPO protein expression by targeting LPO mRNA. However, BLV does not directly regulate the expression of LTF, alpha-LA, or beta-LG proteins through BLV-miRNAs.

Amyloid-like aggregation of recombinant ß-lactoglobulin at pH 3.5 and 7.0: Is disulfide bond removal the key to fibrillation?

Functional nanofibrils from globular proteins are usually formed by heating for several hours at pH 2.0, which induces acidic hydrolysis and consecutive self-association. The functional properties of these micro-metre-long anisotropic structures are promising for biodegradable biomaterials and food applications, but their stability at pH > 2.0 is low. The results presented here show that modified ß-lactoglobulin can also form nanofibrils by heating at neutral pH without prior acidic hydrolysis; the key is removing covalent disulfide bonds via precision fermentation. The aggregation behaviour of various recombinant ß-lactoglobulin variants was systemically studied at pH 3.5 and 7.0. The suppression of intra- and intermolecular disulfide bonds by eliminating one to three out of the five cysteines makes the non-covalent interactions more prevalent and allow for structural rearrangement. This stimulated the linear growth of worm-like aggregates. Full elimination of all five cysteines led to the transformation of worm-like aggregates into actual fibril structures (several hundreds of nanometres long) at pH 7.0. This understanding of the role of cysteine in protein-protein interactions will help to identify proteins and protein modifications to form functional aggregates at neutral pH.

Site-Specific Characterization of Heat-Induced Disulfide Rearrangement in Beta-Lactoglobulin by Liquid Chromatography-Mass Spectrometry.

Disulfides are important for maintaining the protein native structure, but they may undergo rearrangement in the presence of free Cys residues, especially under elevated temperatures. Disulfide rearrangement may result in protein aggregation, which is associated with in vivo pathologies in organisms and in vitro protein functionality in food systems. In a food context, it is therefore important to understand the process of disulfide rearrangement on a site-specific level in order to control aggregation. In the present study, a liquid chromatography-mass spectrometry (LC-MS)-based bottom-up site-specific proteomic approach was optimized to study disulfide rearrangements in beta-lactoglobulin (ß-LG) under different heat treatments (60-90 °C). Artifactual disulfide rearrangement observed during sample preparation using a conventional protocol was detected and minimized by blocking the remaining free Cys residues with iodoacetamide in the presence of urea after heat treatment. Use of endoproteinase Glu-C for enzymatic hydrolysis allowed, for the first time, identification and comparison of the relative intensity of all theoretically possible ß-LG disulfide cross-links formed by the heat treatments. Non-native disulfides were formed from heat treatment at approx. 70 °C where ß-LG started to unfold, while higher levels of inter-molecular disulfide links were formed at ≥80 °C, in agreement with ß-LG aggregation detected by size exclusion chromatography analysis. Collectively, the Cys residues of the surface-located native disulfide Cys66-Cys160 were proposed to be more reactive, participating in heat-induced disulfide rearrangement, compared to other Cys residues. The abundant signal of non-native disulfide bonds containing Cys66, especially Cys66-Cys66, observed after heating suggested that Cys66 is a key disulfide-linked Cys residue in ß-LG participating in heat-induced inter-molecular disulfide bonds and the corresponding protein aggregation.

Analysis of peptides in a sheep beta lactoglobulin hydrolysate as a model to evaluate the effect of peptide amino acid sequence on bioactivity.

Fungal protease FPII was found to hydrolyse sheep ß-lactoglobulin (ß-Lg), and the hydrolysate exhibited substantial antioxidant and ACE inhibition bioactivities. From analysis of the peptide sequences in the hydrolysate in relation to bioactivity, synthetic peptides corresponding to four regions of sequence in ß-Lg (LAFNPTQLEGQCHV, DTDYKKYLLF, LDAQSAPLRVY and VEELKPTPE) were analysed for bioactivity. Additional synthetic peptides were designed to examine the bioactivity of different parts of the above four sequences, and the effect of amino acid substitutions on bioactivity. The results show that parts of the peptide sequences contribute differently to bioactivity and substitution of amino acids has a substantial effect on antioxidant and ACE inhibition activities.

Development and characterization of in vitro self-assembled recombinant human follicle stimulating hormone originated from goat mammary epithelial cells.

Follicle stimulating hormone (FSH), composed of FSHα and FSHß subunits, is essential for female follicle development and male spermatogenesis. The recombinant human FSH (rhFSH) products on the market are mainly generated from mammalian cells and are expensive. Large animal mammary gland bioreactors are urgently needed to produce large amounts of rhFSH. However, there are currently no effective methods to prepare rhFSH by large animals mainly due to the fact that excessive accumulation of FSH might cause many adverse effects in animals. We herein report the development and characterization of functional self-assembled rhFSH produced in goat mammary epithelial cells (GMECs). FSHα and FSHß stably expressed in Chinese hamster ovary (CHO) cell lines were secreted into culture medium and well glycosylated. Importantly, FSHα and FSHß expressed apart were able to assemble into functional FSH. We next inserted human FSHα or FSHß gene separately into goat ß-Lactoglobulin locus in GMECs by CRISPR/Cas9. Inactive FSHα and FSHß subunits expressed from GMECs assembled into rhFSH as analyzed by His-tag pull down assay. Functional assessment of rhFSH by cAMP induction assay, mouse ovulation induction and rat ovarian weight gain experiments showed that the bioactivity of self-assembled rhFSH expressed by GMECs was comparable to that of Gonal-F both in vitro and in vivo. Our study demonstrated that FSHα and FSHß can be separately expressed and assembled into functional rhFSH, and provided the basis for future preparing FSH by goat mammary gland bioreactor with less health problems on the producing animals.

The heteropolysaccharide of Mangifera indica fruit: Isolation, chemical profile, complexation with ß-lactoglobulin and antioxidant activity.

A 91 kDa heteropolysaccharide (F2) was isolated from Mangifera indica fruit via extraction with H2O, purification by C2H5OH, starch removal and ion exchange chromatography. This polymer was made up mostly of Ara, Gal, Glc, Rha, Xyl, and GalA in a 37: 29: 9:3:2:19 molar proportion. It inherited a small backbone containing GalpA and Rhap units substituted with very large side chains containing differently linked Ara and Gal units plus esterified gallic acid (GA) residue. Several enzymes generated oligosaccharides including (i) Ara2-10Ac6-22, (ii) Gal1-8Ac5-26 and (iii) GA1Gal1Ac7 were characterized. This polysaccharide, which showed dose dependent antioxidant activity, exhibited synergism with gallic acid, and formed a complex (K = 1.2 × 106 M-1) with ß-lactoglobulin. Accordingly, H2O treatment produces a polysaccharide with desired biochemical properties; this could be effective in designing innovative functional food with flexible makeup.

Polymorphisms of leptin, beta-lactoglobulin and pituitary transcription factor have no effect on milk characteristics in crossbred cows / Polimorfismos da leptina, beta-lactoglobulina e fator de transcrição da hipófise não afetam as características do leite em vacas mestiças

O objetivo deste trabalho foi identificar polimorfismos genéticos de leptina, ß-lactoglobulina e fator de transcrição pituitária (PIT1) e avaliar seus efeitos na composição química e na contagem de células somáticas de leite de vacas leiteiras mestiças que vivem em um clima quente. Um total de 291 vacas leiteiras mestiças foram investigadas. Foram coletadas amostras de sangue para extração de DNA e amostras de leite. As amostras foram classificadas em três grupos genéticos: 12/ (42), 34/ (83) e 78/ (166) Holandês x Guzerá. As frequências de alelos e genótipos foram determinadas e o equilíbrio Hardy-Weinberg foi avaliado. Foram realizadas análises da composição do leite (gordura, proteína, lactose e extracto seco desengordurado), contagem de células somáticas e rendimento leiteiro. Os grupos genéticos e os polimorfismos genéticos para cada gene foram utilizados como efeitos fixos na análise. O único polimorfismo encontrado em equilíbrio de Hardy-Weinberg foi para o genótipo da ß-lactoglobulina. No presente estudo, era esperado que a maioria das variáveis de composição variasse entre os genótipos. Já se sabe que os cruzamentos dão origem a animais com características fenotípicas e genotípicas. No entanto, os polimorfismos não influenciaram a composição e a qualidade do leite nas vacas 12/ , 34/ e 78/ Holstein x Guzerá mantidas em um clima quente.(AU)

The engineered ß-lactoglobulin with complementarity to the chlorpromazine chiral conformers.

Chlorpromazine (CPZ) is a phenothiazine acting as dopamine antagonist. Aside from application in schizophrenia therapy, chlorpromazine is found to be a putative inhibitor of proteins involved in cancers, heritable autism disorder and prion diseases. Four new ß-lactoglobulin variants with double or triple substitutions: I56F/L39A, F105L/L39A, I56F/L39A/M107F or F105L/L39A/M107F changing the shape of the binding pocket were produced and their chlorpromazine binding properties have been investigated by X-ray crystallography, circular dichroism, isothermal titration calorimetry and thermophoresis. The CD spectra and crystal structures revealed that mutations do not affect the protein overall structure but in comparison to WT protein, variants possessing I56F substitution had lower stability while mutation F105L increased melting temperature of the protein. The new variants showed affinity to chlorpromazine in the range 4.2-15.4 × 103 M-1. The CD spectra and crystal structures revealed complementarity of the binding pocket shape, to only one chlorpromazine chiral conformer. The (aR)-CPZ was bonded to variants containing I56F substitution while variants with F105L substitution preferred (aS)-CPZ.

Effect of supplementation of cows diet with linseed and fish oil and different variants of ß-lactoglobulin on fatty acid composition and antioxidant capacity of milk.

BACKGROUND: The aim of this study was to determine the influence of polymorphic variants of ß-lactoglobulin in cows supplemented with linseed and fish oil on the fatty acid composition and antioxidant capacity of milk. From the herd of 320 Polish Holstein Friesian cows three groups of cows were selected according to the variants of ß-LG (ß-LGAA, ß-LGBB, ß-LGAB). During the first 7 days (the initial period) all the cows were fed the same total mixed ration (TMR) diet. From day 8 to 28,150 g fish oil and 250 g linseed (FOL) was added to the TMR diet of each cow. RESULTS: The results showed that the diet supplemented with FOL was effective in reducing atherogenic and thrombogenic indices. Introducing supplementation improved the antioxidant capacity: higher concentration of C18:2cis-9 trans-11, C20:5 n-3, C22:6 n-3, bioactive whey proteins and vitamin soluble in fat has been recorded. The results showed that ß-LGAA was associated with lower levels of atherogenic and thrombogenic indices and higher concentration of C22:5 n-6, phospholipids and ß-carotene. ß-LGBB favours a higher content of C18:1trans-11, C18:2cis-9 trans-11 and lactoferrin. ß-LGAB was associated with higher concentrations of C20:5 n-3, Lysozyme, α-retinol, α-tocopherol and total antioxidant status. CONCLUSION: Modification of the diet of cows with fish oil and linseed significantly influenced fatty acid composition and antioxidant properties of milk. The effect of ß-LG phenotype on the fatty acid composition and antioxidant capacity of milk is variable, which could partly be the result of a ß-LG phenotype × diet interaction.

Oral administration of bovine milk derived extracellular vesicles attenuates arthritis in two mouse models.

SCOPE: This study shows the effect of bovine milk derived extracellular vesicles (BMEVs) on spontaneous polyarthritis in IL-1Ra-deficient mice and collagen-induced arthritis. METHODS AND RESULTS: BMEVs were isolated from semi-skimmed milk by ultracentrifugation and the particle size was around 100 nm by dynamic light scattering and electron microscopy. BMEVs expressed exosome marker CD63, immunoregulatory microRNA's (miR-30a, -223, -92a), and milk-specific beta-casein and beta-lactoglobulin mRNA. In vitro, PKH-67-labeled BMEVs were taken up by RAW264.7, splenocytes, and intestinal cells as determined by flow cytometry and confocal microscopy. IL-1Ra(-/-) mice received BMEVs by daily oral gavage starting at wk 5 till 15 after birth and collagen-induced arthritis mice via their drinking water starting 1 wk before immunization till day 40. Macroscopically, BMEV treatment delayed the onset of arthritis and histology showed diminished cartilage pathology and bone marrow inflammation in both models. BMEV treatment also reduced the serum levels of MCP-1 and IL-6 and their production by splenic cells. BMEV treatment diminished the anticollagen IgG2a levels, which was accompanied by reduced splenic Th1 (Tbet) and Th17 (RORγT) mRNA. CONCLUSION: This is the first report that oral delivery of BMEVs ameliorates experimental arthritis and this warrants further research to determine whether this beneficial effect can be seen in rheumatoid arthritis patients.

Polymorphism of three milk protein genes in Mexican Jersey cattle

The objective was to estimate the allelic and genotypic frequencies, genetic diversity and polymorphic information content for the β-casein, κ-casein and β-lactoglobulin genes. Blood and frozen semen samples were collected from 453 Jersey individuals registered by the Mexican Jersey Cattle Association. Twenty eight breed specific SNP primers for whole genes were used. The B allele of κ-casein had higher frequency (0.69) than the A (0.26) and E (0.05). For β-lactoglobulin, the highest frequency was for B (0.72), followed by A and C alleles (0.26 and 0.02, respectively). The β-casein allele with the highest frequency was A² (0.71), followed by A¹ (0.19), A³ (0.05), B (0.04) and C (0.01). The average genetic diversity (He) was 0.53. The average locus effective allele number was 1.79. These results indicate a high allelic diversity for κ-caseín, β-casein and β-lactoglobulin that could be included in breeding programs in the population studied, aimed to improve the milk quality traits of economic importance.

Bovine chromosomal regions affecting rheological traits in rennet-induced skim milk gels.

Optimizing cheese yield and quality is of central importance to cheese manufacturing. The yield is associated with the time it takes before the gel has an optimal consistency for further processing, and it is well known that gel formation differs between individual milk samples. By identifying genomic regions affecting traits related to rennet-induced gelation, the aim of this study was to identify potential candidate genes affecting these traits. Hence, rennet-induced gelation, including rennet coagulation time, gel strength, and yield stress, was measured in skim milk samples collected from 379 animals of the Swedish Red breed using low-amplitude oscillation measurements. All animals had genotypes for almost 621,000 segregating single nucleotide polymorphisms (SNP), identified using the Bovine HD SNPChip (Illumina Inc., San Diego, CA). The genome was scanned for associations, haplotypes based on SNP sets comprising highly associated SNP were inferred, and the effects of the 2 most common haplotypes within each region were analyzed using mixed models. Even though the number of animals was relatively small, a total of 21 regions were identified, with 4 regions showing association with more than one trait. A major quantitative trait locus for all traits was identified around the casein cluster explaining between 9.3 to 15.2% of the phenotypic variation of the different traits. In addition, 3 other possible candidate genes were identified; that is, UDP-N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyl-transferase 1 (GALNT1), playing a role in O-glycosylation of κ-casein, and 2 cathepsins, CTSZ and CTSC, possibly involved in proteolysis of milk proteins. We have shown that other genes than the casein genes themselves may be involved in the regulation of gelation traits. However, additional analysis is needed to confirm these results. To our knowledge, this is the first study identifying quantitative trait loci affecting rennet-induced gelation of skim milk through a high-density genome-wide association study.

Construction of a recombinant human insulin expression vector for mammary gland-specific expression in buffalo (Bubalus bubalis) mammary epithelial cell line.

The aim of the present study was construction of mammary gland specific expression vector for high level of human insulin (hINS) expression in transgenic buffalo for therapeutic use. We have constructed mammary gland specific vector containing human insulin gene and there expression efficiency was checked into in vitro cultured buffalo mammary epithelial cells (BuMECs). Human pro-insulin coding region was isolated from human genomic DNA by intron skipping PCR primer and furin cleavage site was inserted between B-C and C-A chain of human insulin by overlap extension PCR. A mammary gland-specific buffalo beta-lactoglobulin promoter was isolated from buffalo DNA and used for human insulin expression in BuMEC cells. The construct was transfected into BuMECs by lipofection method and positive transgene cell clones were obtained by G418 selection after 3 weeks. Expression of hINS in transfected cells were confirmed by RT-PCR, Immunocytochemistry, Western Blotting and ELISA. The pAcISUBC insulin-expressing clones secreted insulin at varying levels between 0.18 - 1.43 ng/ml/24 h/2.0 × 10(6) cells.

Effect of fish oil and linseed supplementation on the protein composition of milk from cows with different ß-lactoglobulin phenotypes.

BACKGROUND: The objective of this study was to determine the impact of fish oil and linseed (FOL) supplements on the protein fraction levels of milk from cows with different phenotypes of ß-lactoglobulin. RESULTS: After 21 days of supplementation the study showed significantly higher concentrations of whey proteins, especially lysozyme (144% increase) and lactoferrin (45.5% increase), compared with milk from control cows (total mixed ration with no supplemented FOL). A reverse trend was demonstrated for casein, casein index and casein number (lower level). The most favourable change (higher level), in terms of lactoferrin, α-lactalbumin and bovine serum albumin contents in milk, was recorded in cows with the BB variant of ß-lactoglobulin. The highest level of lysozyme was recorded in the milk of cows with the AB variant of ß-lactoglobulin. CONCLUSION: The combined supplementation of fish oil and linseed had a positive impact on whey proteins in cow's milk. In addition, the phenotype of ß-lactoglobulin also played a role in milk protein composition. There is therefore a clear indication that nutritional experiments should take into account not only food supplements but also the genetic variants of ß-lactoglobulin.

Mammary-specific ablation of the calcium-sensing receptor during lactation alters maternal calcium metabolism, milk calcium transport, and neonatal calcium accrual.

To meet the demands for milk calcium, the lactating mother adjusts systemic calcium and bone metabolism by increasing dietary calcium intake, increasing bone resorption, and reducing renal calcium excretion. As part of this adaptation, the lactating mammary gland secretes PTHrP into the maternal circulation to increase bone turnover and mobilize skeletal calcium stores. Previous data have suggested that, during lactation, the breast relies on the calcium-sensing receptor (CaSR) to coordinate PTHrP secretion and milk calcium transport with calcium availability. To test this idea genetically, we bred BLG-Cre mice with CaSR-floxed mice to ablate the CaSR specifically from mammary epithelial cells only at the onset of lactation (CaSR-cKO mice). Loss of the CaSR in the lactating mammary gland did not disrupt alveolar differentiation or milk production. However, it did increase the secretion of PTHrP into milk and decreased the transport of calcium from the circulation into milk. CaSR-cKO mice did not show accelerated bone resorption, but they did have a decrease in bone formation. Loss of the mammary gland CaSR resulted in hypercalcemia, decreased PTH secretion, and increased renal calcium excretion in lactating mothers. Finally, loss of the mammary gland CaSR resulted in decreased calcium accrual by suckling neonates, likely due to the combination of increased milk PTHrP and decreased milk calcium. These results demonstrate that the mammary gland CaSR coordinates maternal bone and calcium metabolism, calcium transport into milk, and neonatal calcium accrual during lactation.

Dasatinib inhibits mammary tumour development in a genetically engineered mouse model.

Src family kinase activity is elevated in a number of human cancers including breast cancer. This increased activity has been associated with aggressive disease and poor prognosis. Src inhibitors are currently in clinical development with a number of trials currently assessing their activity in breast cancer. However, the results to date have been disappointing and a further evaluation of the preclinical effects of Src inhibitors is required to help establish whether these agents will be useful in the treatment of breast cancer. In this study we investigate the effects of dasatinib, which is a potent inhibitor of Src family kinases, on the initiation and development of breast cancer in a genetically engineered model of the disease. The mouse model utilized is driven by expression of activated ErbB-2 under the transcriptional control of its endogenous promoter coupled with conditional loss of Pten under the control of Cre recombinase expressed by the BLG promoter. We show that daily oral administration of dasatinib delays tumour onset and increases overall survival but does not inhibit the proliferation of established tumours. The striking difference between the dasatinib-treated group of tumours and the vehicle controls was the prominent squamous metaplasia that was seen in six out of 11 dasatinib-treated tumours. This was accompanied by a dramatic up-regulation of both E-cadherin and ß-catenin and down-regulation of ErbB-2 in the dasatinib-treated tumours. Dasatinib also inhibited both the migration and the invasion of tumour-derived cell lines in vitro. Together these data support the argument that benefits of Src inhibitors may predominate in early or even pre-invasive disease.

Expression of humanized anti-Her2/neu single-chain IgG1-like antibody in mammary glands of transgenic mice.

A system for production of single-chain antibody in mammary glands of mice was developed on the basis of a hybrid gene constructed from the coding sequence of anti-Her2/neu single-chain antibody inserted into the first exon of the sheep beta-lactoglobulin gene. Lines of transgenic mice were obtained that expressed humanized single-chain anti-Her2/neu IgG1-like antibody in their milk. These antibodies interact with Her2/neu antigen with high affinity (K(d) = 0.4 nM). The expression level of the transgene depended on its integration site in the genome but not on the copy number. The transgene had no toxic effect on the mice and was stably inherited, at least for two generations. The results reveal new opportunities of producing single-chain antibodies in the milk of animals.

Milk protein fragments induce the biosynthesis of macedocin, the lantibiotic produced by Streptococcus macedonicus ACA-DC 198.

The aim of the present work was to study the mode of the induction of the biosynthesis of macedocin, the lantibiotic produced by Streptococcus macedonicus ACA-DC 198. Macedocin was produced when the strain was grown in milk but not in MRS or M17 broth. No autoinduction mechanism was observed. Production did not depend on the presence of lactose or galactose in the culture medium or on a coculture of the producer strain with macedocin-sensitive or macedocin-resistant strains. Induction seemed to depend on the presence of one or more heat-stable protein components produced when S. macedonicus ACA-DC 198 was grown in milk. The partial purification of the induction factor was performed by a combination of chromatography methods, and its activity was confirmed by a reverse transcription-PCR approach (RT-PCR). Mass spectrometric (MS) and tandem mass spectrometric (MS/MS) analyses of an induction-active fraction showed the presence of several peptides of low molecular mass corresponding to fragments of alpha(S1)- and beta-casein as well as beta-lactoglobulin. The chemically synthesized alpha(S1)-casein fragment 37-55 (2,253.65 Da) was proven to be able to induce macedocin biosynthesis. This is the first time that milk protein degradation fragments are reported to exhibit a bacteriocin induction activity.

DNA methylation changes in cell line from beta-lactoglobulin gene targeted fetus.

The gene targeting combined somatic cell nuclear transfer is very useful in agriculture and medicine. Epigenetic modification of DNA by methylation is significant in regulating gene expression during mammalian development. During gene targeting, epigenetic status of donor cell nuclei may be changed in a series of processes, including homologous recombination, cell selection and cloning. We examined DNA methylation of six genes (beta-actin, VEGF, oct4, TERT, H19 and Igf2) and a repetitive sequence art2 in blg(+/-) cell line from beta-lactoglobulin (BLG) gene targeted fetus and the cells used for BLG gene targeting serve as control. The results demonstrated that the widespread changes of DNA methylation were found in blg(+/-) cell line. But the degree of variation was different. DNA methylation of VEGF in blg(+/-) was noticeably decreased. These observations suggest that DNA methylation variations may impact gene expression and finally induce abnormalities and lethality in later developmental stages.

Bactericidal activity of LFchimera is stronger and less sensitive to ionic strength than its constituent lactoferricin and lactoferrampin peptides.

The innate immunity factor lactoferrin harbours two antimicrobial moieties, lactoferricin and lactoferrampin, situated in close proximity in the N1 domain of the molecule. Most likely they cooperate in many of the beneficial activities of lactoferrin. To investigate whether chimerization of both peptides forms a functional unit we designed a chimerical structure containing lactoferricin amino acids 17-30 and lactoferrampin amino acids 265-284. The bactericidal activity of this LFchimera was found to be drastically stronger than that of the constituent peptides, as was demonstrated by the need for lower dose, shorter incubation time and less ionic strength dependency. Likewise, strongly enhanced interaction with negatively charged model membranes was found for the LFchimera relative to the constituent peptides. Thus, chimerization of the two antimicrobial peptides resembling their structural orientation in the native molecule strikingly improves their biological activity.