Recent advances in interactions between polyphenols and plant cell wall polysaccharides as studied using an adsorption technique.

Polyphenols include flavonoids, phenolic acids, tannins and lignans which are known to have antioxidant, UV protection and antimicrobial properties. Among them the most commonly investigated are flavonoids and phenolic acids, which, due to their plant origin, may interact with the plant cell wall (PCW) components, specifically with its polysaccharides. Knowledge concerning the nature of the interactions between these components may be used in the production of functional food or in the development of food packaging materials with additional properties. The content of polyphenols in such products is responsible for their colour and taste, and may also act as a natural preservative. On the other hand, the PCW components may have protective role of polyphenols which has impact on their release in the human digestive system. Therefore, this review is an attempt to summarize the current state of knowledge that emerged after 2017 concerning the interaction of PCW components with polyphenols, with a particular focus on hemicellulose and pectin.

A comparison of the production of antimicrobial peptides and proteins by Galleria mellonella larvae in response to infection with two Pseudomonas aeruginosa strains differing in the profile of secreted proteases.

The work presents identification of antimicrobial peptides and proteins (AMPs) in the hemolymph of Galleria mellonella larvae infected with two Pseudomonas aeruginosa strains (ATCC 27,853 and PA18), differing in the profile of secreted proteases. The insects were immunized with bacteria cultivated in rich (LB) and minimal (M9) media, which resulted in appearance of a similar broad set of AMPs in the hemolymph. Among them, 13 peptides and proteins were identified, i.e. proline-rich peptides 1 and 2, lebocin-like anionic peptide 1 and anionic peptide 2, defensin/galiomicin, cecropin, cecropin D-like peptide, apolipophoricin, gallerimycin, moricin-like peptide B, lysozyme, apolipophorin III, and superoxide dismutase. Bacterial strain- and/or medium-dependent changes in the level of proline-rich peptide 1, anionic peptide 1 and 2, moricin-like peptide B, cecropin D-like and gallerimycin were observed. The analysis of the expression of genes encoding cecropin, gallerimycin, and galiomicin indicated that they were differently affected by the bacterial strain but mainly by the medium used for bacterial culture. The highest expression was found for the LB medium. In addition to the antibacterial and antifungal activity, proteolytic activity was detected in the hemolymph of the P. aeruginosa-infected insects. Based on these results and those presented in our previous reports, it can be postulated that the appearance of AMPs in G. mellonella hemolymph can be triggered not only by P. aeruginosa pathogen associated molecular patterns (PAMPs) but also by bacterial extracellular proteases secreted during infection. However, although there were no qualitative differences in the set of AMPs depending on the P. aeruginosa strain and medium, differences in the level of particular AMPs synthesized in response to the bacteria used were observed.

Pseudomonas aeruginosa alkaline protease exhibits a high renaturation capability.

Thermally induced unfolding and renaturation capability of alkaline proteases (AprA) of three Pseudomonas aeruginosa strains, i.e. ATCC 27853 and two clinical isolates, was examined. Sequence analyses demonstrated a high level of aprA genes identity (99.24-99.8%) in these bacterial strains. The proteases retained 45-60% and 15% of their activity after pre-treatment at 60oC and 80oC, respectively, whereas pre-incubation at 90-95oC resulted in a higher level of activity than at 80oC. Zymography analyses and immunoblotting with AprA antiserum suggested a high thermostability and renaturation capability of the studied enzymes in comparison to another P. aeruginosa protease, elastase B. An intrinsic capability of renaturation of P. aeruginosa AprA was confirmed by fluorescence spectra of the native, thermally denatured, and renatured enzyme. The value of the fluorescence intensity of the denatured and subsequently cooled enzyme recovered to about 80% of the value of the native protein fluorescence intensity. Moreover, pre-incubation of the enzyme at 60oC and 90oC exerted only a slight effect on the intensity of absorbance and the shape of the amide I band, as demonstrated by Fourier transform infrared (FTIR) spectroscopy performed after subsequent cooling of the pre-treated enzyme. The results indicated a high renaturation capability of the P. aeruginosa AprA proteins.

[Metalloproteases and their inhibitors: role in pathogenesis of selected examples]. / Metaloproteinazy i ich inhibitory: rola w patogenezie na wybranych przykladach.

Proteolytic enzymes and their inhibitors are crucial in host-pathogen interaction. Metalloproteases secreted by pathogenic microbes play an important role in destroying not only host tissues but also their immune proteins. Metalloproteinase inhibitors, in contrast, may serve as effective therapeutic agents, which is especially important because of the increasing number of microorganisms resistant to known antibiotics. The role of metalloproteases produced by the bacterium Pseudomonas aeruginosa in the colonization of the host organism is described. Attention has also been paid to the role of inhibitors of these enzymes in defense responses and underlined their potential role in inhibiting the development of infection.

[Different faces of phenoloxidase in animals]. / Rózne oblicza oksydazy fenolowej u zwierzat.

Phenoloxidases are oxidoreducting enzymes whose main function is the oxidation of phenols. The term phenoloxidase is often used interchangeably to describe three different enzymes: tyrosinase (EC 1.14.18.1), catechol oxidase, and laccase. Of these, only tyrosinase has two activities: (1) oxygenase activity to hydroxylate monophenols to ortho-diphenols and (2) oxidase activity responsible for further oxidation of ortho-diphenols to ortho-quinones. Tyrosinase is a key enzyme involved in the melanogenesis process, resulting in the formation of black-brown eumelanin and yellow-red feomelanin. In addition to the pigmentary role, human melanin protects against harmful ultraviolet radiation, while in invertebrate animals melanin is involved in the process of cuticle hardening, wound healing, clot formation, maintenance of intestinal homeostasis and defense reactions. In invertebrates, the tyrosinase is synthesized as a proenzyme that is activated by a serine proteases' cascade known as the phenoloxidase system. This system is considered as one of the innate immunity mechanisms.