Exploring the potential anti-thyroid activity of Acetyl-L-carnitine: Lactoperoxidase inhibition profile, iodine complexation and scavenging power against H2O2. Experimental and theoretical studies.

L-Acetylcarnitine (ALC), a versatile compound, has demonstrated beneficial effects in depression, Alzheimer's disease, cognitive impairment, and other conditions. This study focuses on its antithyroid activity. The precursor molecule, L-carnitine, inhibited the uptake of triiodothyronine (T3) and thyroxine (T4), and it is possible that ALC may reduce the iodination process of T3 and T4. Currently, antithyroid drugs are used to control the excessive production of thyroid hormones (TH) through various mechanisms: (i) forming electron donor-acceptor complexes with molecular iodine, (ii) eliminating hydrogen peroxide, and (iii) inhibiting the enzyme thyroid peroxidase. To understand the pharmacological properties of ALC, we investigated its plausible mechanisms of action. ALC demonstrated the ability to capture iodine (Kc = 8.07 ± 0.32 x 105 M-1), inhibit the enzyme lactoperoxidase (LPO) (IC50 = 17.60 ± 0.76 µM), and scavenge H2O2 (39.82 ± 0.67 mM). A comprehensive physicochemical characterization of ALC was performed using FTIR, Raman, and UV-Vis spectroscopy, along with theoretical DFT calculations. The inhibition process was assessed through fluorescence spectroscopy and vibrational analysis. Docking and molecular dynamics simulations were carried out to predict the binding mode of ALC to LPO and to gain a better understanding into the inhibition process. Furthermore, albumin binding experiments were also conducted. These findings highlight the potential of ALC as a therapeutic agent, providing valuable insights for further investigating its role in the treatment of thyroid disorders.

Modified Lactoperoxidase System as a Promising Anticaries Agent: In Vitro Studies on Streptococcus mutans Biofilms.

The lactoperoxidase (LPO) system shows promise in the prevention of dental caries, a common chronic disease. This system has antimicrobial properties and is part of the non-specific antimicrobial immune system. Understanding the efficacy of the LPO system in the fight against biofilms could provide information on alternative strategies for the prevention and treatment of caries. In this study, the enzymatic system was modified using four different (pseudo)halide substrates (thiocyanate, thiocyanate-iodide mixture, selenocyanate, and iodide). The study evaluated the metabolic effects of applying such modifications to Streptococcus mutans; in particular: (1) biofilm formation, (2) synthesis of insoluble polysaccharides, (3) lactate synthesis, (4) glucose and sucrose consumption, (5) intracellular NAD+ and NADH concentrations, and (6) transmembrane glucose transport efficiency (PTS activity). The results showed that the LPO-iodide system had the strongest inhibitory effect on biofilm growth and lactate synthesis (complete inhibition). This was associated with an increase in the NAD+/NADH ratio and an inhibition of glucose PTS activity. The LPO-selenocyanate system showed a moderate inhibitory effect on biofilm biomass growth and lactate synthesis. The other systems showed relatively small inhibition of lactate synthesis and glucose PTS but no effect on the growth of biofilm biomass. This study provides a basis for further research on the use of alternative substrates with the LPO system, particularly the LPO-iodide system, in the prevention and control of biofilm-related diseases.

Augmenting apoptosis-mediated anticancer activity of lactoperoxidase and lactoferrin by nanocombination with copper and iron hybrid nanometals.

There is an urgent need in the medicinal fields to discover biocompatible nanoformulations with low cytotoxicity, which provide new strategies for promising therapies for several types of tumors. Bovine lactoperoxidase (LP) and lactoferrin (LF) have recently attracted attention in medicine for their antitumor activities with recognized safety pattern. Both LP and LF are suitable proteins to be coated or adsorbed to Cu and Fe nanometals for developing stable nanoformulations that boost immunity and strong anticancer effects. New nanometals of Cu and Fe NPs embedded in LP and LF forming novel nanocombinations of LP-CNPs and LF-FNPs had a spherical shape with an average nanosize of about 21 nm. The combination of LP-CNPs and LF-FNPs significantly exhibited the highest growth inhibitory efficacy, in terms of effectively lowering the half-maximal inhibitory concentration (IC50) values, against Caco-2, HepG2 and MCF7 cells comparing to nanometals, LP, LF and individual nanoproteins (LP-CNPs or LF-FNPs). The highest apoptotic effect of this nanocombination (LP-CNPs and LF-FNPs) was confirmed by the highest percentages of annexin-stained apoptotic cells and G0 population with the strongest alteration in the expression of two well-characterized apoptosis guards (p53 and Bcl-2) and the maximum suppression in the proliferation marker (Ki-67). Also, the in silico analysis predicted that LP-CNPs and LF-FNPs enhanced AMP-activated protein kinase (AMPK, p53 activator) activity and inhibited cancer migration-related proteases (cathepsin B and matrix metalloproteinase (MMP)-9). Our results offer for the first time that these novel nanocombinations of LP and LF were superior in their selectivity and apoptosis-mediating anticancer activity to Cu and Fe nanometals as well as the free form of these proteins or their individual nanoforms.

The Impact of Mouthwash on the Oropharyngeal Microbiota of Men Who Have Sex with Men: a Substudy of the OMEGA Trial.

Mouthwash is a commonly used product and has been proposed as an alternative intervention to prevent gonorrhea transmission. However, the long-term effects of mouthwash on the oral microbiota are largely unknown. We investigated the impact of 12 weeks of daily mouthwash use on the oropharyngeal microbiota in a subset of men who have sex with men who participated in a randomized trial comparing the efficacy of two alcohol-free mouthwashes for the prevention of gonorrhea. We characterized the oropharyngeal microbiota using 16S rRNA gene sequencing of tonsillar fossae samples collected before and after 12 weeks of daily use of Listerine mouthwash or Biotène dry mouth oral rinse. Permutational multivariate analysis of variance (PERMANOVA) was used to assess differences in oropharyngeal microbiota composition following mouthwash use. Differential abundance testing was performed using ALDEx2, with false-discovery rate correction. A total of 306 samples from 153 men were analyzed (Listerine, n = 78 and Biotène, n = 75). There was no difference in the overall structure of the oropharyngeal microbiota following Listerine or Biotène use (PERMANOVA P = 0.413 and P = 0.331, respectively). Although no bacterial taxa were significantly differentially abundant following Listerine use, we observed a small but significant decrease in the abundance of both Streptococcus and Leptotrichia following Biotène use. Overall, our findings suggest that daily use of antiseptic mouthwash has minimal long-term effects on the composition of the oropharyngeal microbiota. IMPORTANCE Given the role of the oral microbiota in human health, it is important to understand if and how external factors influence its composition. Mouthwash use is common in some populations, and the use of antiseptic mouthwash has been proposed as an alternative intervention to prevent gonorrhea transmission. However, the long-term effect of mouthwash use on the oral microbiota composition is largely unknown. We found that daily use of two different commercially available mouthwashes had limited long-term effects on the composition of the oropharyngeal microbiota over a 12-week period. The results from our study and prior studies highlight that different mouthwashes may differentially affect the oral microbiome composition and that further studies are needed to determine if mouthwash use induces short-term changes to the oral microbiota that may have detrimental effects.

Milk lactoperoxidase decreases ID1 and ID3 expression in human oral squamous cell carcinoma cell lines.

Milk consumption may modify the risk of squamous cell carcinoma. The role of milk to modulate the gene expression in oral squamous cell carcinoma cells has not been investigated so far. Here, HSC2 oral squamous carcinoma cells were exposed to an aqueous fraction of human milk and a whole-genome array was performed. Among the genes that were significantly reduced by human and cow milk were the DNA-binding protein inhibitor 1 (ID1), ID3 and Distal-Less Homeobox 2 (DLX2) in HSC2 cells. Also, in TR146 oral squamous carcinoma cells, there was a tendency towards a decreased gene expression. Upon size fractionation, lactoperoxidase but not lactoferrin and osteopontin was identified to reduce ID1 and ID3 in HSC2 cells. Dairy products and hypoallergenic infant formula failed to decrease the respective genes. These data suggest that milk can reduce the expression of transcription factors in oral squamous carcinoma cells.

Preparation and characterization of novel nanocombination of bovine lactoperoxidase with Dye Decolorizing and anti-bacterial activity.

Interaction between nanoparticles (NPs) and protein is particularly important due to the formation of dynamic nanoparticle-protein complex. The current study indicated that silica NPs were able to induce conformational modification in the adsorbed lactoperoxidase (LPO) which in turns degrades the synthetic dyes. The maximum degradation efficiency was recorded for the LPO modified silica NPs in the presence of H2O2 comparing with either free LPO or silica NPs. Degradation efficiency of crystal violet and commassie blue R250 after 6 h was assessed to be 100(%). Also, degradation efficiency of Congo red reached 90.6% and 79.3% in the presence and absence of H2O2, respectively, however methyl red degradation efficiency recorded 85%. The viability assay experiment indicated that the IC50 value of the LPO modified silica NPs on human fibroblast cells reached 2.8 mg/ml after 48 h incubation. In addition to dye removal, the LPO modified silica NPs were able to inhibit the antibiotic resistant bacterial strains (Salmonell typhii, Staphylococcus areus, Pseudomonas aureginosa, E. coli, Proteus sp. and streptococcus sp.) at concentrations up to 2.5 mg/ml with inhibition activity about 95%. These findings emphasized that the ability of LPO for degradation of the synthetic dyes after adsorption on silica NPs besides it could be a promising agent with potent inhibitory effect targeting a wide range of multidrug resistant bacteria.

The Significance of Lactoperoxidase System in Oral Health: Application and Efficacy in Oral Hygiene Products.

Lactoperoxidase (LPO) present in saliva are an important element of the nonspecific immune response involved in maintaining oral health. The main role of this enzyme is to oxidize salivary thiocyanate ions (SCN-) in the presence of hydrogen peroxide (H2O2) to products that exhibit antimicrobial activity. LPO derived from bovine milk has found an application in food, cosmetics, and medical industries due to its structural and functional similarity to the human enzyme. Oral hygiene products enriched with the LPO system constitute an alternative to the classic fluoride caries prophylaxis. This review describes the physiological role of human salivary lactoperoxidase and compares the results of clinical trials and in vitro studies of LPO alone and complex dentifrices enriched with bovine LPO. The role of reactivators and inhibitors of LPO is discussed together with the possibility of using nanoparticles to increase the stabilization and activity of this enzyme.

Flaminal® versus Flamazine® in the treatment of partial thickness burns: A randomized controlled trial on clinical effectiveness and scar quality (FLAM study).

Although partial thickness burns are the most frequently reported burn injuries, there is no consensus on the optimal treatment. The objective of this study was to compare the clinical effectiveness and scar quality of Flaminal® Forte to silver sulfadiazine (Flamazine®) in the treatment of partial thickness burns. In this two-arm open label multicenter randomized controlled trial, adult patients with acute partial thickness burns and an affected total body surface area of less than 30% were randomized between Flaminal® Forte and Flamazine® and followed for 12 months. Dressing changes in the Flamazine® group were performed daily, and in the Flaminal® group during the first 3 days post burn and thereafter every other day until complete wound healing or surgery. Forty-one patients were randomly allocated to Flaminal® Forte and 48 patients to Flamazine®. The primary outcome was time to wound healing, which did not differ between the groups: median 18 days with Flaminal® Forte (range 8-49 days) versus 16 days with Flamazine® (range 7-48 days; p = 0.24). Regarding the secondary outcomes during hospital admission, there were no statistically significant differences between the groups concerning need for surgery, pain scores, pruritus, or pain-related and anticipatory anxiety. More patients in the Flaminal® group developed wound colonization (78% versus 32%, p < 0.001), but the treatment groups did not differ regarding the incidence of local infections and use of systemic antibiotics. In terms of scar quality, no statistically significant differences between both treatment groups were found regarding subjective scar assessment (Patient and Observer Scar Assessment Scale (POSAS)), scar melanin and pigmentation (DermaSpectrometer®), and scar elasticity and maximal extension (Cutometer®) during 12 month postburn. In conclusion, time to wound healing did not differ, but the use of Flaminal® Forte seemed favorable because less dressing changes are needed which lowers the burden of wound care.

Lactoperoxidase immobilization on silver nanoparticles enhances its antimicrobial activity.

Lactoperoxidase (LPO) is an antimicrobial protein present in milk that plays an important role in natural defence mechanisms during neonatal and adult life. The antimicrobial activity of LPO has been commercially adapted for increasing the shelf life of dairy products. Immobilization of LPO on silver nanoparticles (AgNPs) is a promising way to enhance the antimicrobial activity of LPO. In the current study, LPO was immobilized on AgNPs to form LPO/AgNP conjugate. The immobilized LPO/AgNP conjugate was characterized by various biophysical techniques. The enhanced antibacterial activity of the conjugate was tested against E. coli in culture at 2 h intervals for 10 h. The results showed successful synthesis of spherical AgNPs. LPO was immobilized on AgNPs with agglomerate sizes averaging approximately 50 nm. The immobilized conjugate exhibited stronger antibacterial activity against E. coli in comparison to free LPO. This study may help in increasing the efficiency of lactoperoxidase system and will assist in identifying novel avenues to enhance the stability and antimicrobial function of LPO system in dairy and other industries.

Antimicrobial actions of dual oxidases and lactoperoxidase.

The NOX/DUOX family of NADPH oxidases are transmembrane proteins generating reactive oxygen species as their primary enzymatic products. NADPH oxidase (NOX) 1-5 and Dual oxidase (DUOX) 1 and 2 are members of this family. These enzymes have several biological functions including immune defense, hormone biosynthesis, fertilization, cell proliferation and differentiation, extracellular matrix formation and vascular regulation. They are found in a variety of tissues such as the airways, salivary glands, colon, thyroid gland and lymphoid organs. The discovery of NADPH oxidases has drastically transformed our view of the biology of reactive oxygen species and oxidative stress. Roles of several isoforms including DUOX1 and DUOX2 in host innate immune defense have been implicated and are still being uncovered. DUOX enzymes highly expressed in the respiratory and salivary gland epithelium have been proposed as the major sources of hydrogen peroxide supporting mucosal oxidative antimicrobial defenses. In this review, we shortly present data on DUOX discovery, structure and function, and provide a detailed, up-to-date summary of discoveries regarding antibacterial, antiviral, antifungal, and antiparasitic functions of DUOX enzymes. We also present all the literature describing the immune functions of lactoperoxidase, an enzyme working in partnership with DUOX to produce antimicrobial substances.

Clinical concentrations of peroxidases cause dysbiosis in in vitro oral biofilms.

BACKGROUND AND OBJECTIVE: Little is known about the initiation of dysbiosis in oral biofilms, a topic of prime importance for understanding the etiology of, and preventing, periodontitis. The aim of this study was to evaluate the effect of different concentrations of crevicular and salivary peroxidase and catalase on dysbiosis in multispecies biofilms in vitro. MATERIAL AND METHODS: The spotting technique was used to identify the effect of different concentrations of myeloperoxidase, lactoperoxidase, erythrocyte catalase, and horseradish peroxidase in salivary and crevicular fluid on the inhibitory effect of commensals on pathobiont growth. Vitality-quantitative real-time PCR was performed to quantify the dysbiotic effect of the peroxidases (adjusted to concentrations found in periodontal health, gingivitis, and periodontitis) on multispecies microbial communities. RESULTS: Agar plate and multispecies ecology experiments showed that production of hydrogen peroxide (H2 O2 ) by commensal bacteria decreases pathobiont growth and colonization. Peroxidases at concentrations found in crevicular fluid and saliva neutralized this inhibitory effect. In multispecies communities, myeloperoxidase, at the crevicular fluid concentrations found in periodontitis, resulted in a 1-3 Log increase in pathobionts when compared with the crevicular fluid concentrations found in periodontal health. The effect of salivary lactoperoxidase and salivary myeloperoxidase concentrations was, in general, similar to the effect of crevicular myeloperoxidase concentrations. CONCLUSIONS: Commensal species suppress pathobionts by producing H2 O2 . Catalase and peroxidases, at clinically relevant concentrations, can neutralize this effect and thereby can contribute to dysbiosis by allowing the outgrowth of pathobionts.

Efficiency of novel nanocombinations of bovine milk proteins (lactoperoxidase and lactoferrin) for combating different human cancer cell lines.

Bovine lactoperoxidase (LPO) and lactoferrin (LF) are suitable proteins to be loaded or adsorbed to chitosan nanoparticles (NPs) for preparing stable nanoformulations with potent anticancer activity. In the present study, nanocombinations of LPO and LF revealed improvement in their stability and activity compared to single (free or nanoformulated) bovine proteins. The coating or loading of LPO-loaded NPs with LF resulted in the highest synergistic cytotoxicity effect against Caco-2, HepG-2, MCF-7 and PC-3 cells in comparison with other NPs and free proteins without causing toxicity toward normal cells. This synergistic improvement in the anticancer activity was apoptosis-dependent that was confirmed by severe alterations in cellular morphology, high percentage of annexin-stained cells and sub-G1 populations as well as nuclear staining with orange fluorescence of treated cancer cells. Additionally, significant alterations in the expression of well characterized cellular proliferation and apoptosis guards (NF-κB, Bcl-2 and p53) in these NPs-treated cancer cells compared to 5-fluorouracil (5-FU) treated cells. Our findings provide for the first time that these new synergistic nanoformulated forms of LPO and LF were superior in their selective apoptosis-mediating anticancer effect than free form of these proteins and 5-FU. LF coating or loading of LPO-loaded NPs present as promising therapy for cancer.

Effects of lactoferrin and lactoperoxidase-containing food on the oral microbiota of older individuals.

The oral microbiota influences health and disease states. Some gram-negative anaerobic bacteria play important roles in tissue destruction associated with periodontal disease. Lactoferrin (LF) and lactoperoxidase (LPO) are antimicrobial proteins found in saliva; however, their influence on the whole oral microbiota currently remains unknown. In this randomized, double-blinded, placebo-controlled study, the effects of long-term ingestion of LF and LPO-containing tablets on the microbiota of supragingival plaque and tongue coating were assessed. Forty-six older individuals ingested placebo or test tablets after every meal for 8 weeks. The relative abundance of bacterial species was assessed by 16S rRNA gene high-throughput sequencing. Most of the bacterial species in supragingival plaque and tongue coating that exhibited significant decreases in the test group were gram-negative bacteria, including periodontal pathogens. Decreases in the total relative abundance of gram-negative organisms in supragingival plaque and tongue coating correlated with improvements in assessed variables related to oral health, such as oral malodor and plaque accumulation. Furthermore, there was significantly less microbiota diversity in supragingival plaque at 8 weeks in the test group than in the placebo group and low microbiota diversity correlated with improvements in assessed variables related to oral health. These results suggest that LF and LPO-containing tablets promote a shift from a highly diverse and gram-negative-dominated to a gram-positive-dominated community in the microbiota of supragingival plaque and tongue coating. This microbial shift may contribute to improvements in oral health, including oral malodor and state of the gingiva.

Two novel roles of buffalo milk lactoperoxidase, antibiofilm agent and immunomodulator against multidrug resistant Salmonella enterica serovar Typhi and Listeria monocytogenes.

The increasing occurrence of multidrug resistant bacteria causing bacteremia infection, constitutes a major health problem, difficult-to-treat bacteremia due to its ability to form biofilm. Buffalo milk lactoperoxidase (BMLpo) is effective and safe to use as bacteriostatic agent. The MIC of BMLpo and amikacin were used to evaluate the antibiofilm activity against resistant L. monocytogenes and S. typhi. Prophylactic effects of BMLpo against L. monocytogenes and S. typhi bacteremia in vivo have been tested and ELISA test used to evaluate serum cytokines. Significant antibiofilm activity of BMLpo observed against the highest biofilm producer isolates. Our results showed that the prophylactic effect of BMLpo in BALB/c mice bacteremic model. A significant clearance of L. monocytogenes and S. typhi, investigated in blood and different organs tissues in BMLpo-treated infected groups when compared to the non-treated groups. Further, analysis of serum cytokines levels revealed that BMLpo prophylaxis modulates their release in different way when it compared to the control. This study showed, BMLpo effects as an alternative antibiofilm agent to compact gram negative pathogens, and protects the host against bacteremia infection. Moreover, the BMLpo role as an immunomodulatory. These investigations indicated the BMLpo crucial role in the practical clinical applications.

Effectiveness of casein phosphopeptide-amorphous calcium phosphate and lysozyme, lactoferrin, and lactoperoxidase in reducing Streptococcus mutans counts in dentinal caries.

This study compared the capacity of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) to that of a combination of lysozyme, lactoferrin, and lactoperoxidase (LLL) in root canal disinfectant for reducing the Streptococcus mutans counts from dentinal caries. Forty human permanent third molars were selected, and flat dentin surfaces were created. Carious lesions were induced using a microbiological model. The specimens were randomly divided into 2 groups (n = 20) according to the type of agent used: group 1, CPP-ACP; group 2, LLL. The S mutans counts were performed before application and after the first, second, and third applications of the agents. The duration of each application was 3 minutes. Carious dentin specimens were homogenized, diluted, and seeded onto mitis salivarius-bacitracin plates for viable counts of S mutans. Results showed that there was no significant reduction in the number of S mutans in group 1 after the applications of CPP-ACP (P > 0.05). In group 2, a significant reduction of S mutans was observed after the third application of LLL (P < 0.01). These results indicate that 3 applications of LLL enzymes can be used to reduce the number of S mutans in dentinal caries lesions.

Effects of lactoferrin and lactoperoxidase-containing food on the oral hygiene status of older individuals: A randomized, double blinded, placebo-controlled clinical trial.

AIM: Lactoferrin and lactoperoxidase have antimicrobial effects against oral pathogens. This randomized, double-blinded, placebo-controlled parallel group study tested the efficacy of a lactoferrin and lactoperoxidase-containing tablet (LF + LPO tablet) in improving the oral hygiene status of older individuals. METHODS: A total of 46 participants (31 nursing home residents and 15 healthy older individuals) were randomly assigned to receive either lactoferrin and lactoperoxidase-containing tablets or placebo tablets, and were asked to suck on a tablet after every meal for 8 weeks. Oral and bacteriological assessments were carried out at baseline, 4 weeks and 8 weeks. RESULTS: A total of 47 participants (test group n = 20; mean age 80.4 ± 6.4 years; placebo group n = 17; mean age 85.9 ± 6.7 years) were included in the efficacy analysis. In the test group, the total number of bacteria in the tongue coating was significantly reduced at 4 and 8 weeks compared with that at baseline, and the number of Porphyromonas gingivalis and Fusobacterium nucleatum was significantly reduced at 8 weeks. The total number of bacteria and the number of P. gingivalis in the supragingival plaque were significantly reduced at 8 weeks. Furthermore, there was a significant difference in the change in the number of P. gingivalis in supragingival plaque at 8 weeks between the two groups. CONCLUSIONS: Lactoferrin and lactoperoxidase-containing tablet ingestion showed antibacterial effects on periodontal bacteria present in the tongue coating and supragingival plaque, indicating that long-term ingestion could improve the oral hygiene of older individuals. Geriatr Gerontol Int 2017; 17: 714-721.

Comparative Analysis of the Antiviral Activity of Camel, Bovine, and Human Lactoperoxidases Against Herpes Simplex Virus Type 1.

Lactoperoxidase is a milk hemoprotein that acts as a non-immunoglobulin protective protein and shows strong antimicrobial activity. Bovine milk contains about 15 and 7 times higher levels of lactoperoxidase than human colustrum and camel milk, respectively. Human, bovine, and camel lactoperoxidases (hLPO, bLPO, and cLPO, respectively) were purified as homogeneous samples with specific activities of 4.2, 61.3, and 8.7 u/mg, respectively. The optimal working pH was 7.5 (hLPO and bLPO) and 6.5 (cLPO), whereas the optimal working temperature for these proteins was 40 °C. The K m of hLPO, cLPO, and bLPO were 17, 16, and 19 mM, and their corresponding V max values were 2, 1.7, and 2.7 µmol/min ml. However, in the presence of H2O2, the K m values were 11 mM for hLPO and cLPO and 20 mM for bLPO, while the corresponding V max values were 1.17 for hLPO and 1.4 µmol/min ml for cLPO and bLPO. All three proteins were able to inhibit the herpes simplex virus type 1 (HSV-1) in Vero cell line model. The relative antiviral activities were proportional to the protein concentrations. The highest anti-HSV-1 activity was exhibited by bLPO that inhibited the HSV particles at a concentration of 0.5 mg/ml with the relative activity of 100%.

Disorder in milk proteins: structure, functional disorder, and biocidal potentials of lactoperoxidase.

This article continues a series of reviews on the abundance and roles of intrinsic disorder in milk proteins. Besides caseins, which are the major proteinaceous constituents of any milk that can be isolated by isoelectric precipitation, milk contains a set of soluble whey proteins, such as ß-lactoglobulin, α-lactalbumin, serum albumin, immunoglobulins, lactoferrin, lactoperoxidase, glycomacropeptide, and proteose peptone (the last two are soluble casein derivatives). Lactoferrin and lactoperoxidase (LPO) are known to possess prominent biocidal activity, serving as efficient antibiotics and antiviral agents against a wide spectrum of bacteria, fungi, and viruses. LPO is a heme-containing peroxidase expressed as preproprotein. The mature protein has a single catalytic domain, structure of which is known for a protein isolated from several species. Functionally, LPO is a crucial component of the LPO system that includes LPO, hydrogen peroxide (H2O2), and thiocyanate (SCN(-)), being a well-studied, naturally occurring antimicrobial system in milk that is effective against many microorganisms and some viruses. Although various aspects of LPO structure and function are rather well studied and were subjects of several recent reviews, the abundance and potential functional roles of intrinsically disordered regions in this protein have never being addressed as of yet. The major goal of this article is to fill this gap and to show how intrinsic disorder is encoded in the amino acid sequence of LPO, and how intrinsic disorder is related to functions of this important milk protein.

Short communication: The influence of solids concentration and bleaching agent on bleaching efficacy and flavor of sweet whey powder.

Recent studies have demonstrated the effect of bleaching conditions and bleaching agent on flavor and functional properties of whey protein ingredients. Solids concentration at bleaching significantly affected bleaching efficacy and flavor effects of different bleaching agents. It is not known if these parameters influence quality of sweet whey powder (SWP). The purpose of this study was to determine the effects of solids concentration and bleaching agent on the flavor and bleaching efficacy of SWP. Colored cheddar whey was manufactured, fat separated, and pasteurized. Subsequently, the whey (6.7% solids) was bleached, concentrated using reverse osmosis (RO) to 14% solids, and then spray dried, or whey was concentrated before bleaching and then spray dried. Bleaching treatments included a control (no bleaching, 50 °C, 60 min), hydrogen peroxide (HP; 250 mg/kg, 50 °C, 60 min), benzoyl peroxide (50 mg/kg, 50 °C, 60 min), lactoperoxidase (20 mg/kg of HP, 50 °C, 30 min), and external peroxidase (MaxiBright, DSM Food Specialties, Delft, the Netherlands; 2 dairy bleaching units/mL, 50 °C, 30 min). The experiment was repeated in triplicate. Sensory properties and volatile compounds of SWP were evaluated by a trained panel and gas chromatography-mass spectrometry, respectively. Bleaching efficacy (norbixin destruction) and benzoic acid were measured by HPLC. Differences in bleaching efficacy, sensory and volatile compound profiles, and benzoic acid were observed with different bleaching agents, consistent with previous studies. Solids concentration affected bleaching efficacy of HP, but not other bleaching agents. The SWP from whey bleached with HP or lactoperoxidase following RO had increased cardboard and fatty flavors and higher concentrations of lipid oxidation compounds compared with SWP from whey bleached before RO. The SWP bleached with benzoyl peroxide after RO contained less benzoic acid than SWP from whey bleached before RO. These results indicate that solids concentration at bleaching and bleaching agent affect quality of SWP.

Chitosan coating incorporated with the lactoperoxidase system: an active edible coating for fish preservation.

BACKGROUND: As a result of consumers' concerns about chemicals there is a particular interest in the food industry to use natural bio-preservatives such as antimicrobial enzymes for antimicrobial packaging. Based on the antimicrobial activity of the lactoperoxidase system (LPOS), the present study evaluated the coating effect of LPOS incorporated into chitosan solution (CH) on the quality and shelf life extension of rainbow trout during refrigerated storage (4 ± 1 °C), for a period of 16 days. RESULTS: The results indicated that samples of the CH+LPOS group had significantly lower numbers of Shewanella putrefaciens, Pseudomonas fluorescens, and psychrotrophic and mesophilic bacteria than did the CH and control group during the entire storage period. Total volatile basic nitrogen (TVB-N) levels for the CH+LPOS samples (22.07 mg 100 g(-1)) did not exceed the limit of consumption (30-35 mg N 100 g(-1)), while the CH (31.03 mg 100 g(-1) ) and control groups (37.78 mg 100 g(-1) ) reached this level at days 12 and 16, respectively. Thiobarbituric acid values of the CH and CH+LPOS samples, ranged between 0.49 and 0.51 on day 0 and 4.59-4.66 mg kg(-1) on day 16, were significantly lower (P < 0.05) than the corresponding values of the control samples (0.47 on day 0 to 4.78 mg kg(-1) on day 16 of storage) during the chilled storage period. CONCLUSION: The coating treatments (CH and CH+LPOS) extended the shelf life of trout fillets by at least 4 days as compared to the control samples, so that they showed moderate to high acceptability in all investigated sensory attributes even on the 16th day of storage.